Hi Gardeners
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| Coming soon |
It’s a beautiful spring day here, with temperatures in the low 60’s. I was outside sitting in the sun and
exploring the yard. Besides the
snowdrops I have a single white crocus open. Lots of bulbs have popped above ground and I
see lamium and sedum growing already along with weeds like dandelion and ground
ivy. I removed some of the walnuts from
flower beds but I’m being cautious and leaving most of the leafy mulch on the
beds. We could still get some very
cold weather.
There’s been an unusually bitter cold spell in Europe this
week. I’m feeling sorry for the gardeners
over there whose plants may not be used to the cold, especially this late in
the season. They had snow as far south
as Rome.
My brother has returned to his sub-tropical paradise in Australia. After being in the cold here those 90-degree
days they are having there will be a shock to his system. His wife has been
maintaining the farm while he was gone, and they had some power outages after storms
which required her to start the generator, so she’s pleased he has returned. Good job – Christine!
I’m getting excited about spring now. I’m going to try some plants I’ve never grown
before as I do every year. This year I’m
growing pimpernel, Chinese foxglove, Blue Woodruff (Asperula orientalis),Blue Lace flower (Trachymene coerulea) and Night Phlox ( Zaluzianskya capensis). What
new flowers are you going to try this year?
At least grow one new thing every year.
There’s a lot of words in this week’s blog so I’ll let you get
reading.
Pruning evergreens
As the weather warms gardeners get out in the yard and want to do
something. It may still be to risky to
plant, but hey it’s the perfect time to prune right? It is the perfect time to prune some, but not
all plants. Some evergreens can be
pruned now so let’s discuss those needled or conifer evergreens.
I’ve seen many a botched evergreen pruning and I’m sure you have
too. All those shrubs with dead stems
sticking up, lopped unnatural looking trees and hedges with big dead areas
exposed. Before you prune the needled
evergreen plants – as well as any plant- you need to know what species it is
because different species require different styles of pruning.
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| Arborvitae hedge on the left |
Evergreens aren’t all pine trees and they certainly aren’t
Christmas trees. The main needle leafed
evergreen plant families are pine (Pinus),
spruce (Picea), firs (Abies), Yew (Taxus), Juniper (Juniperus),
and cedars (Thuja). It is easy to
identify some species within these plant families but in other cases even
experts have a hard time identifying individual species, especially if they are
not common ones. And in addition, some common names suggest a family that the
tree doesn’t really belong in. So, don’t
worry too much if you can’t identify what species of fir you have, just whether
you have a pine or a fir.
I am going to give you a brief identification guide to each
species so you can tell them apart. But
if you still aren’t sure what species the tree or shrub you want to prune belongs
to get a good identification guide or ask an experienced person to help you.
Selective pruning to improve a tree or shrubs shape, make it fuller
or keep it in bounds is different from shearing. With selective pruning you prune one branch
at a time, after examining it for the best place to cut. You are trying to
maintain or encourage a natural looking form for the plant.
Shearing is what you do to hedges or topiary. It takes
off branches all at the same level, generally without examining each branch.
Plant’s will not look natural after that type of pruning. Some evergreens can’t be sheared or you will
end up with big bare areas or a dead plant.
With all types of evergreens it’s best not to remove more
than 20 to 30% of a tree or shrub at a time.
Most evergreens cannot be taken back to the ground and recover, unlike
some other woody plants. If a tree or
shrub is vastly overgrown cutting it back to what you think is a manageable
size may expose wood that no longer has the ability to put out new growth. After any remaining needles mature and fall
you’ll have a bare stump. In these cases
it’s best to simply remove the plant and replace it.
Time to prune
In the spring, before new needles begin to pop out is a good time
to prune many evergreens. The exception
is pines. You must wait until new
shoots, called candles, have almost fully expanded before pruning pines. Another time when most evergreens can be
pruned is mid-summer, when it’s hot and many needled evergreens are
semi-dormant. Once again that’s not a
good time to prune pines.
Of course, you can remove dead branches, broken branches or
branches that are obstructing a view, drive or walkway anytime. Take those
branches right off close to the tree, at the branch collar. You don’t need to use pruning paint on the
cut surface. It’s normal for many evergreens to have dead lower branches. Also,
many evergreen branches are bare toward the trunk with new growth toward the
branch tip.
When shearing certain evergreens into hedges or ornamental forms
do it in late spring or early summer after there has been some new growth. The plants will have time to make new buds
for next years growth and you’ll be able to more clearly see where your limits
are to avoid dead areas being exposed.
Pines
Pines always have needles in bundles. A little papery sheath binds together
anywhere from 2 to 5 needles at their base.
Pines have cones of various shapes; the shape as well as the number and
length of the needles can help identify the species. Many cones of pines have a
prickly point on the end of each scale on the cone.
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| Pine |
Wait to prune pines until a new shoot, called a candle, with
lighter green needles has pushed out on most branches. This will probably be late spring. To shape
or control growth remove a third to a half of each candle. If you prune beyond the new growth where
older darker needles are, you will eventually have a bare branch there.
Every few years, depending on species, pines drop some of the
older needles. That’s why pine branches
are generally bare for long expanses toward the trunk. If you prune beyond the
new growth area on the branch tip eventually you’ll have no needles on that
branch at all. If for some reason you
need a branch to be shorter than where the new growth ends you may as well take
it off all the way to the trunk.
Pines can’t be sheared.
They should be allowed to form a natural shape with only modest pruning.
Never top pines- that is cut straight
across the top. If a pine has 2 or more “leaders”,
the upright branches near the top that expand the height of the tree, all but
one should be removed.
Spruces
Spruces have short needles attached singly to the branch with a
little stub that remains after the needle falls off. That makes the branch feel quite rough with its
numerous protrusions. Spruce needles are generally 4 sided with a blunt tip,
surround the entire branch and are square looking when cross cut. When crushed spruce needles have a pungent
odor that can remind you of cat pee.
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| Spruce |
Spruces should need little pruning. It’s the normal habit of some spruces for the
bottom branches to die after a few years. These can simply be cut off at the
trunk. If a branch has no green needles
or visible buds it isn’t coming back. Clean
up pruning, removing dead limbs, and limbs you want permanently, completely
gone can be done in early spring or really at just about any time.
To shape spruce you can trim back new growth in the spring by
about 1/3 or take each branch back to a healthy lateral (cross) branch. If you can see the dormant buds on the limb a
branch can be cut back to just before that bud.
Firs
Firs are the trees with the delightful smell associated with
Christmas and are often sold for Christmas trees. They are less frequent in the landscape than
pines or spruces. Firs have single
needles attached to the branch with little suction cup like bases. When they fall off they leave a slight pit on
the branch, but the branch will feel smooth.
Fir needles often have one or two white lines on the back of the
flattened needle. Fir cones stand
upright on the top of a branch; the cone scales fall away and leave a “core”
protruding from the branch for a while.
The Douglas fir is not a true fir but is in a species of its own (Psuedotsuga menziesii). It has flat, soft, single needles attached to
the branch. The needles narrow at the
base and when they fall off they leave raised scar, but are not as prominent as
the bumps on a spruce. Douglas fir cones
hang downward on the underside of branches and are unique because 3 pointed
seed bracts protrude from each scale on the cone. Douglas firs grow to be the second largest of
our trees, second only to Sequoias.
Both firs and Douglas firs are pruned much like the spruce. They
shouldn’t be sheared, rather they should be carefully pruned to make sure they
retain a natural look. New growth can be pruned back by about a third, to a
cross branch or to a dormant bud.
Cedar
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| White cedar |
The tree family Thuja is
also called Cedar or Arborvitae and they are common landscape plants. Northern White Cedar is our most common
species. However, what is confusing is
that there is a southern tree family called White Cedar (Chamaecyparis) which looks very similar to our Thuja species. Occasionally
some species and cultivars of this family are sold as ornamentals although they
aren’t very hardy in the north.
Northern White Cedar has flattened overlapping scale-like
leaves. On the underside of the leaves
you can find tiny raised spots called resin glands. The trees have tiny cones in clusters near
the branch tips. Arborvitae comes in a
variety of shapes, from the natural tree like form to upright dense windbreak
forms and rounded globes that stay small.
It has a pleasant smell, reddish bark and wood that is hard and dense.
Cedars come in many forms, and the form may dictate the type of
pruning you’ll want to do. The good news
is that cedars are very amenable to pruning as they have many dormant buds
along their stems. Try not to remove
more than 20 percent of a cedar at any time though.
If you need to remove a lot of the cedar do it in early spring,
before new growth begins. This will
stimulate new spring growth that will hide the pruning cuts. If the cedar has a dense shape, like a
constantly sheared hedge, there may be a dead area in the center. Do not expose or cut back into that area or
you may have a permanent dead spot there.
If you are cutting back the height of a tree form of cedar cut it
back to a crotch near your desired height, making sure that’s not in a dead
area. If you are shearing
cedar/arborvitae into a hedge, make sure the bottom of the hedge is wider than
the top. Bottom branches always in the
shade of the upper branches will eventually die. Shearing cedar into shapes and so on is fine,
if you don’t cut back into a dead area.
Some live needles should always remain at the tip of branches.
Cedars typically have a reddish or purplish tint to the foliage
after winter chilling. This is normal
and doesn’t need to be pruned off.
Junipers
Junipers are known for their prickliness. Adding to the name confusion one species of
Juniper has the common name of Eastern Redcedar. It forms a tree shape and has overlapping
rows of flattened scale like needles when mature but when the plant is young
the needles are spiky and sharp.
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| Juniper |
Common juniper forms a more shrub-like sprawling form and the
needles, arranged in whorls of 3, stay sharp and prickly. The common identifying characteristic of
Junipers besides their prickly needles is their blue, berry–like cones. These are used to flavor gin. Birds spread juniper “berries” and they are
often found growing along roads and in abandoned fields.
Junipers, like cedars, come in a variety of shapes. And like cedar most junipers will have a dead
area in the center of the plant or near the trunk. When pruning one should always leave some
live needles on branch ends.
Juniper is not quite as forgiving as cedar to pruning. Pruning should be light and done in early
spring. Spreading and groundcover junipers should have limbs trimmed back to a
lateral branch if the plant needs to be reduced in size. Upright junipers should not have more than
20% of their height removed.
Occasionally some forms of juniper are sheared into hedges. If you
are doing this wait until most new growth has opened and only remove a third to
a half of it.
Yews- (and hemlocks)
Yews have soft flat, dark green needles which are paler yellowish
green on the bottom. Their identifying characteristic is that they have red
berry-like cones. They are seldom found in the wild but are common ornamentals
here. They tolerate shade and
trimming. However, yews are extremely
poisonous to livestock and pets eating foliage or bark and children consuming
the berries. Use care planting them in the landscape.
Yews are pretty forgiving to pruners and easy to prune. They have two flushes of growth every year
and the ability to develop buds on old wood.
I gave seen yews cut back to close to the ground and live, but this is
not recommended because it takes a long time for them to recover.
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| Yew |
Prune yews for size and shaping in early spring before growth
starts. You may need to prune again in early summer after the first growth
flush. If a yew is really overgrown I
would not take more than half of it off in one year.
If yews are sheared into hedges do it in early spring, and after
the first growth flush up to August. Don’t
prune yews after August because this encourages new growth that will likely be
killed in winter because it hasn’t time to harden off.
Hemlocks are pruned like yews.
However, take only about 30% off at a time.
Fertilizing houseplants
As the
sun gets stronger and the days get longer your houseplants are waking from
their winter dormancy and stretching. Some tropical plants grow all year round,
but many plants slow their growth or cease growth during fall and winter
months. This is especially true if you
rely on natural light from windows. But when new growth is seen in the spring
it’s time to think about fertilizer.
Whether
you need to fertilize houseplants depends on many things. If the plant is already growing vigorously
and too much growth could be a problem, then fertilizer probably isn’t
needed. Remember plants make their own
food from the process of photosynthesis.
The fertilizer we supply them is more like us taking vitamins, it
replaces certain minerals that the plants may be lacking because they are not
growing in natural mineral soil. Some
plants seem to be able to exist very well without much supplementation.
If a
plant is already touching the ceiling and sinking it into the floor isn’t an
option, then it’s probably not a good idea to fertilize it. However, if the plant isn’t growing well,
appears weak and sparsely leafed, then fertilizer may be needed. If you have flowering plants like African
violets, geraniums, hibiscus or begonias, fertilization will allow them to put
on a good bloom show.
Fertilization
may also increase the plants resistance to disease and insects, just as proper
nutrition boosts our immune system. However,
a plant that’s suffering badly from insects or disease should not be fertilized
until those conditions have cleared up.
When you see some new growth beginning that is the time to fertilize.
To
fertilize houseplants, the best method is to use a water-soluble fertilizer
formulated for houseplants or a general-purpose plant food that includes
houseplants on its label. Read and
follow the label instructions carefully for mixing the fertilizer with
water. There are even organic houseplant
fertilizers such as fish emulsion on the market.
Some
houseplants like citrus and orchids do better with carefully formulated
fertilizers just for them. Blooming houseplants like hibiscus, fuchsia,
kalanchoe and others should have fertilizer formulated for blooming plants.
There
are 3 numbers on the package of any fertilizer.
These are the percentages of nitrogen, phosphorus and potash, the major
nutrients plants need. For houseplants choose a 1:2:1 percentage ratio such as
5-10-5 or 10-20-10. Also, a balanced ratio is good, such as 10-10-10. Look for a fertilizer that also contains
micro-nutrients such as manganese, boron, zinc, molybdenum, copper and cobalt
in it’s list of ingredients.
If you
are re-potting houseplants you can mix some extended release fertilizer
granules into the potting medium. This
will generally give you 3-4 months of good fertilization. In larger pots you may also be able to top
dress- sprinkle on top-the fertilizer granules and lightly scratch them into
the potting medium. There are also fertilizer spikes which you stick in the
ground. Read and follow label
directions.
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| Streptocarpus need fertilizing for good bloom |
I don’t
recommend experimenting with homemade fertilizers for houseplants. Commercial
fertilizers are carefully balanced and include trace elements that are hard to
get from random organic matter. Putting food scraps, coffee grounds and other
things in houseplant pots is a good way to attract insects, pets, and
mice. You don’t know what the nutrient
level is in these home-made concoctions.
Generally, they are low in all forms of nutrients. Some scraps like
banana peels are loaded with pesticides.
Put your scraps in the compost pile.
Never
use Epsom salts on houseplants. Epsom salt only furnishes one nutrient-
magnesium. It isn’t a balanced
fertilizer and most houseplants don’t need more than a very tiny amount of
magnesium, which commercial fertilizers provide. Epsom salts can quickly build up in pots
indoors and burn the plant roots.
Never
use sugar, soft drinks, vinegar, liquid coffee or tea as fertilizer, no matter
what the helpful tip you read somewhere says.
These are not fertilizer and could harm your plants. Compost isn’t
fertilizer either, it’s organic matter with some nutrient value but the value
fluctuates widely and there’s no way to know just what nutrient levels it
contains without a lab test. And using urine on houseplants? Not only is it nasty and smelly but it can
severely burn plant foliage and roots.
Fish tank waste water might contain some nitrogen, but it isn’t a
balanced fertilizer.
Commercial
fertilizers, even non- organic ones- will not harm your plants if you use them
as the label directs. Any nutrients
coming from organic matter or “natural” products must be broken down to the
same form as the commercial fertilizers offer before the plant can absorb and
use it. You are just skipping a step for the plant, and you know what nutrients
are in commercial fertilizers and in what ratios.
Do not
make the fertilizer solution too strong! Follow directions. Most commercial fertilizers are formulated
with various “salts” and these build up in the potting medium or soil of
houseplants over time, especially if you use too much too often. You may notice the buildup as a crusty
whitish-yellow substance on the soil surface or on the pot. After a while this accumulated salt will harm
the plant roots and cause the plant to grow poorly or die.
To get
rid of accumulated salts you can re-pot the plant in clean potting medium or
you can leach it. Leaching is placing
the plant in its pot in a sink or bathtub and letting warm water gently flow
through the soil continuously for an hour or two. The water needs to drain out of the pot at
the bottom. Leaching away salts and excess minerals occurs naturally outside
when it rains. When you water your
plants empty the water that drains out of the pot into the saucer a short time
later. If the water is sucked back up
into the pot the salts that were leached out will be re-absorbed too.
Houseplants
need fertilizer once or twice a month from March until the beginning of
September. After September, most
houseplants slow their growth because of lower light intensity and shorter
days. Fertilizing then may cause more
salt build up in the soil. There are
exceptions to this rule, usually for flowering houseplants or plants under
intense artificial light.
Lush,
beautiful houseplants are usually carefully fertilized by their owners. Your houseplants may only need that little
extra boost to really shine.
Free
Master Gardener lesson- flowers and fruit
When
a gardener strolls through his or her garden admiring the flowers they are actually
strolling through a dating site. Nature
developed flowers to allow immobile living things, (plants) to be able to mate
and share genetic material. Flowers are the sex organs of plants. Think about
that when you stick your nose in one. Since plants can’t go looking for love, they use flowers to
attract helpers, or to distribute their male genetic material in the wind or
water.
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| Inside a poppy flower |
The
sharing of genes makes for healthier offspring and allows for changes to be
made to adapt to environments. Most flowers that are showy and/or fragrant are meant to
attract pollinators, little sex servants, to help plants mate. Flowers may “pay” helpers to move pollen from a male plant
part to a female plant part by using delicious nutrient packed pollen or sweet
intoxicating nectar.
There
are plants whose flowers are designed to use the wind or water to procreate. Some
plants can also fertilize themselves if necessary, but they prefer a partner.
Flowers
are very important to humans as they produce most of the food we eat other than
meat, by making fruits and seeds. And
their fruit and seeds feed many of the animals we eat or enjoy sharing our
world with. Flowers, fruits and seeds produce medications, dyes, fragrances and
artistic inspiration.
Now
that you understand how important flowers are, let’s talk about their structure
a bit. There is a wide variation in flower shape, size, and color. But there are some things common to all
flowers. A flower can have all or some
of these parts, receptacle, sepals, petals, stamen and pistil. If it has all of the parts it’s called a
complete flower, if some are missing it’s called an incomplete flower. Simple, huh?
The
receptacle is thickened tissue at the base of a flower that supports it. The ovary of the flower may sit down inside
the receptacle or just above it.
A
flower bud is protected by leaf-like structures called sepals. After a flower opens the sepals may be seen
at it’s base and all of the sepals collectively are called a calyx. In some species of flowers the sepals have
evolved to look exactly like petals.
Lilies and tulips have sepals that look like petals.
Flowers
may also have parts called bracts. Bracts are often colorful and help attract
pollinators to small flowers. The
poinsettia is a good example. The red
parts that many consider flowers are bracts. The flowers are in small yellow
clusters in the center of the bracts. (A complete flower doesn’t have to have
bracts.)
Petals
are the showy parts of most flowers.
They come in a wide variety of shapes, sizes and colors which have
generally evolved to attract certain pollinators or to release pollen
effectively into the wind or water and capture pollen from the air or water.
Some petals have glands which produce fragrances and/or nectar.
Petals
also protect the sex organs of the flower before they mature. Some close around the sex parts in bad
weather or at night. Some petals may
restrict the type of pollinator that gets near the sex organs, if a plant
prefers one pollinator over another.
The sex organs and nectar or pollen may be at the end of a petal “tube”
that only certain insects fit in or have a tongue long enough to reach down.
Some
flower petals have markings which direct pollinators to the sexual organs
inside the flower. The “cat face” on a
pansy flower is a good example. The
lines on the lower petals direct bees to the center of the flower, where they
receive a reward of nectar as they get covered with pollen, which they carry to
the next pansy. Many flowers have a bull’s eye pattern on them that gets darker
closer to the source of nectar or pollen.
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| Pointing to the prize |
Some flower petal markings are invisible to
our eyes but can be seen by bees and other insects. We can see them if we use an ultra violet
light or filter.
Some
flowers are tricksters, using their shape to fool an insect into thinking it’s
another insect, or producing pheromones to make an insect think a mate is
near. Some plants use heat, like the
skunk cabbage, to lure insects into a warm flower for protection in colder
weather. Some collect water in their
flowers for thirsty animals to drink. When
they drink they get dusted with pollen.
Some flowers also trap insects in special pouches for a while. As they
buzz around looking for a way out they get covered in pollen.
The sex organs
To
sex a flower one has only to look inside it. The sex organs are generally in the
middle and are prominent if you know what you are looking for. Some flowers have only one type of sex
organs, male or female. Some flowers have
both male and female parts. A plant that
has separate male and female flowers on the same plant is called monoecious. If a plant has only flowers of one sex,
either male or female, it is called dioecious.
Only plants with female flower parts can produce fruit and seeds.
The
female parts of a flower are called collectively the pistil. The pistil consists of an ovary, ovules,
(unfertilized seeds or egg cells), the style, which is a stalk or tube
connecting the ovary and the stigma. The
stigma is a generally flat area which is the landing pad for pollen. It is somewhat comparable to the vagina in
animals. When it’s ready to receive
pollen it generally turns moist and sticky.
In
some flowers the stigma is large and showy, often a vivid color contrasting
with the petal color. It may have
several lobes or sections. In other
flowers the stigma is barely visible at the end of the style. A flower may have
one or many pistils. (Or no pistils if it is a male flower). A flower with all
female parts is called pistillate.
Female
plant parts produce ova, (eggs), which will turn into seeds if they get
fertilized. The ova are inside an ovary,
attached to a placenta which nourishes them just as animal placentas nourish
embryos. Some flowers have more than one ovary. Each ova consists of two cells, one will make
a plant embryo if fertilized, the other makes a food supply for the embryo and
a covering that encloses them both, (a seed.)
The ovary of the plant is connected to the outside world by the style,
long in some plants, short in others, and at the end of the style is the stigma.
Male
plant parts are called stamens and consist of an anther, which produces pollen
and a filament, the stalk that connects the anther to the flower base. In some flowers the filament is long and
bouncy, in others quite short. A flower
that has only male parts is called staminate. Each flower can have one stamen or
many. (Or a flower can have no male
parts.)
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| Lilies have prominent sex organs |
The anthers
produce pollen. A pollen grain consists
of 3 cells usually enclosed in some protective substance. One cell produces a pollen tube, and the
other two cells are sperm cells that combine with the two cells of the ova if
they are lucky. The pollen of the male
has to get to the stigma of the female plant at just the right time.
Each
species of plant has pollen grains with their own distinctive shape. Pollen is commonly yellow but may be many
different colors. Wind pollinated plants
have small, light pollen grains so they can float on the breeze. Insect pollinated plants have heavier pollen that
is enriched with fats and proteins to better attract insects who want to eat
it. Plants that produce a lot of pollen do so because they expect to sacrifice
some to hungry insects. A little left over pollen will stick to insect hairs or
feet and make it to the next flower so pollination can occur.
Sexual frustration
Even
when a flower has both sexual organs inside it, they may not be able to self-fertilize. Sometimes the pollen and egg cells mature at
different times in the same flower.
Sometimes the sexual parts are arranged within the flower so they are
unlikely to fertilize each other. And
other times the plant produces a hormone that prevents fertilization by a plant
with too similar genetic material.
Nature
made flowers so that plants could share genetic material between plants, which
insures genetic diversity and allows for changes over time. Some flowers are able to self - fertilize if
they have both sexual organs or if the plant has both sexes of flowers. The plant prefers to use this as a last
resort, when unfamiliar pollen isn’t available.
When flowers mate
When a
pollen grain lands on a receptive stigma it’s called pollination. Pollination is
plant mating. But just as when animals
mate, all pollination doesn’t result in fertilization-
or making babies.
When
male flower organs are mature and ready to mate their pollen becomes fluffy,
sticky, and easily detached from the anther.
It may change color, from greenish to bright yellow or from pink to dark
red for example. It’s ready to be picked
up by a visiting insect or other animal.
Plants
have many methods for ensuring that pollen leaves with a pollinator. Some trap insects inside them for a
while. Some make them run a gauntlet of
anthers to reach their reward. Some
anthers are spring loaded and strike the back of an insect that lands on a
stigma. Some flowers even intoxicate
insects so that they buzz around crazily and lounge around in a flower for a
while.
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| Pollination |
Some
flowers dangle their male parts in the wind or drop their pollen into water so
it can make its way to a female plant.
Usually these flowers are not showy; many people fail to recognize them
as flowers. Consider the corn plant. On the top of the plant is the tassle, a
group of all male corn flowers who dangle their sex organs downward toward the
female corn flowers, which are the “silks” at the end of each ear, (also not
very flower-like). Their hope is that the wind will shake pollen down on the
female flower or carry it to another corn plants female flower.
When a
female sex organ on a flower is mature and ready to accept mating the stigma
becomes covered with a clear sticky fluid, the better to grab and hold pollen
grains. Sometimes the stigma swells or
changes color also.
Some
flowers produce pollen or remain receptive to pollen for only a few hours,
others will carry on for many days.
After a
flower has been sexually satisfied, (fertilization has occurred) or gets too
old to reproduce it often changes petal, stigma or anther color so it’s less
attractive to pollinators. Apple blossoms turn pink after fertilization or
aging too much. All those flowers
advertised as having changing colors do so because of aging. Nectar, fragrance
and pollen cease to be produced. The petals wither and fall.
In some
plants there are complete flowers that fail to open. The flowers internally pollinate and
fertilize themselves. These flowers are
called cleistogamous flowers. Usually these flowers are either near or in
the ground. The common violet has both
the normal violet flowers we pick for bouquets and cleistogamous flowers, which
usually appear late in the season down under the plant near the ground.
Making babies
It
turns out that like in much of the animal world hormones, genes, and females
control everything. When pollen lands on
a stigma it has to be ready to accept it, if it’s early or too late it will be
rejected. The female stigma is also able
to regulate which pollen cells would be acceptable mates and rejects those that
are incompatible. This is done through
complex chemical signals and the shape of pollen grains.
Each
grain of pollen contains 3 cells. One
cell is responsible for boring a tube from the top of the stigma where the
pollen grain lands through the style down to the egg inside the ovary of the
flower. One cell carries the genetic
material, similar to an animal’s sperm cell, which forms the embryonic plant
when it unites with the egg. The other
cell will make the food supply around the embryo, which we call a seed.
 |
| Pollen spilling out of a hollyhock flower |
We have
known for a long time that the pollen tube penetrates the hard style of the
female and allows the two sperm cells to slide down and unite with an egg. But until recently we haven’t been able to
probe some of those plant sex secrets, like how the tube manages to find an
ova, and how the female controls the sexual process so mayhem doesn’t result
from the thousands of grains of pollen that typically land on a stigma. I’m
going to describe some of this fascinating new research.
Some
pollen has a tube cell that is actually more aggressive than normal and forces
itself on the female style, trying to ensure the sperm cells accompanying it
win the race. In the long run this is
detrimental to the plant because the ova may not be at the right stage to be
fertilized. But normally when the
pollen landing on the stigma has been vetted by the female flower part,
hormones in the plant lubricate the style and make it softer and the race of
the tubes is on.
Some
plants will have hundreds of tubes snaking through the style, some just one
depending on how many ova are in each ovary, which varies in each plant
species. The tube is guided and
elongated, we recently discovered, by something called MYB transcription
factors, which are similar to substances that turn on genes in animal nervous
systems that make nerves. The tube has to be in contact with the female style
tissue to develop this substance, and “she” turns it on. The tube has to be guided to where an ovum
attaches to the placenta and find the tiny hole where nutrients pass into the
ova from the placenta, and squeeze through that opening.
Scientists
found a way to remove MYB transcription factors from tube cells and discovered
that tubes without it continued to grow, curling around inside the style, never
finding the hole or bursting to release sperm cells. Once again this proves that without female
help males would be lost.
Now
here is where the research gets a bit kinky and just amazingly complex. In order to fertilize the ova the pollen tube
has to explode at just the right instant, and shoot the sperm into the
egg. By using microchips with tiny
channels to stimulate styles and ova openings, researchers found that openings
just tight enough, (the right size for that plant), promoted the explosion. If they tightened an area as the tube pushed
through the simulated style the tube exploded prematurely and since plant sperm
don’t swim, those sperm will never fertilize the ova. (Presumably they were
able to give the tubes MYB transcription factors in the fake style.)
One
researcher said “"Our findings show that a tight grip around the tube does
result in sperm release.” He said that
it was proof that plants can respond to touch.
Now you have to be chuckling here.
But let’s move on.
Once
the sperm hits the ova it needs to fertilize or unite with the two ova cells
quickly. If fertilization is a success
the female plant will not allow any more tubes to penetrate the placenta
hole. If the sperm is a dud, the female
will allow more tubes to enter until one works or the ova is too old. How do scientists know this? Researchers were able to find some mutant
pollen where the tube cell would expand normally, burst at the right time and
release the sperm, but the sperm cells were duds.
The
researchers then were able to mark normal pollen with one color and mutant
pollen with another and watch under a high-power microscope as the race
unfolded. Some ova would end up with
numerous tubes entering them and exploding, until the right one came along.
(Research that the above information
was based on was published in Current Biology and done at Brown
University. Additional research was done
and published by Instituto Gulbenkian de Ciência (IGC), Portugal, and the
University of Montreal and Concordia University. Some research was published in
Science Express of the journal Science.)
Making fruit and seeds
Let’s
make something clear here. A fruit
contains seeds (or was supposed to contain seeds). If it has seeds inside it’s a fruit for
botanical purposes. Fruits range from
juicy watermelons to peanuts to peppers to walnuts to apples to bananas to an
ear of corn. You may consume many fruits
as a vegetable but technically they are fruit.
Each
type of plant has a threshold at which it will allow a fertilized egg to turn
into a seed with its enclosed embryonic plant.
In a plant with a single seed in the ovary one sperm cell uniting with
an egg will probably set seed making in motion.
In an ovary with many egg cells a certain number of eggs may need to be
fertilized before the plant will begin forming a fruit around them and seed
completion is allowed.
Making
a fruit around a seed or group of seeds is energy intensive for a plant. Fruits protect seeds and act as dispersal
mechanisms in many cases. But if a
certain number of seeds aren’t fertilized within the ovary the plant decides
the energy expenditure isn’t worth it and aborts the fruit and immature
seeds.
In a
watermelon, for example, about 100 seeds will need to be fertilized in a
flowers ovary for a watermelon fruit to form and the seeds mature. That means at least 100 grains of pollen had
to fall on that watermelon flowers receptive stigma. See how important our pollinators are?
Some
plants have even fussier pollination/fertilization requirements. An apple flower has a stigma divided into 5
lobes or sections. Two grains of pollen
need to fall on each lobe and successful fertilization occur before an apple
begins forming. Slice open an apple and
you can see the 5 sections of the ovary divided by thick membranes with 2 or
more seeds in each section.
People
have manipulated plants so some form fruits without pollination or
fertilization of a set number of
eggs. That’s how we get seedless fruits.
Types of fruits
The
purpose of fruits is to nourish and protect developing seeds inside them. They keep seeds from drying out until it’s
time for them to germinate. And seeds act as a dispersal system for seeds. Animals carry fruits away or eat them and
poop seeds out somewhere down the line.
A simple fruit is one where a single
flower with one ovary turns into a single fruit. These fruits may have segments with seeds in
them. The stigma of the flower that
produced the segmented fruit had lobes corresponding to the number of fruit
segments.
Simple
fruits can have many shapes. A fruit
with segments divided by papery tissue surrounded by fleshy tissue is called a pome.
An apple is an example. A fleshy
fruit with one central hard “shell” containing a seed is called a drupe.
A peach is an example. A berry has
a juicy interior filled with seeds, often connected to a central core. Tomatoes
are berries. A legume is a hard,
thin seed “pod” filled with several
seeds. Peas and peanuts are an
example. A nut usually has a fleshy outer layer and hard thick inner
layer(shell) protecting a seed. Walnuts
are an example. The winged seeds of
maples, called samara, are a seed
with a wing like papery extension. Some
samara have two seeds like the maple, others have just one.
 |
| Melon fruits are technically berries |
A capsule is a fruit with a thin hard
shell and lots of loose seeds inside when the seed is mature. Poppies have
capsule fruits. Silicle and silique
fruits have a center core (placenta) that the seeds attach to and 2 thin,
shell-like parts that open up like wings to expose the seeds. The silicle is more round in shape than the
silique which is generally long and thin. Radish seeds are siliques. Urticle fruits are a puffy thin walled
fruit with a seed inside. Pigweed has
this type of fruit.
Aggregate fruits come
from flowers that had more than one ovary. Each flower that gets fertilized
forms a tiny fleshy fruit around a seed.
These are the fruits we call berries, even though that term isn’t
botanically correct. Raspberries are an example.
The
strawberry is an example of a very unusual aggregate fruit fruit. Instead of the ovary developing into a fleshy
fruit the receptacle does. The
strawberry seeds are actually tiny individual fruits developing on the outside
of the receptacle. They are called achenes. Achenes are a single seed
without a covering that opens when they are mature.
 |
| The part of the strawberry we eat is a a receptacle Achene fruits develop on the outside with a seed. |
Multiple fruits
develop from flowers with one ovary
that are very close together. Each
flower develops one fruit with a seed but they are so close together they
appear as one fruit. The group of seeds may have a protective cover and they
may be attached to a core. An ear of corn is an example. Each piece of corn silk was a female
flower. The male flowers were at the top
of the plant and are called tassels.
Each fertilized “silk” turned into a kernel of corn. They are arranged
on a cob and covered by a husk.
Learning
the difference between plant fruits can be important when you are trying to
identify plants.
 |
| Each kernel of corn is a fruit. The silks were stigma's, or female sex parts. |
Seeds
Since
this article is already lengthy I won’t go into seeds deeply. Seeds are embryonic plants and their food
supply. The seed coating protects the plant
embryo and its food supply. It can be hard and thick or barely there. Plants
vary in what steps are needed to breach the seed coat so that the seed can
germinate. Some seeds just require a bit
of moisture, some require being swallowed and pooped out, some require fire or
cycles of freezing and thawing before germination can begin.
Inside
each seed is a tiny plant complete with leaves, a stem and the beginning of a
root. Until they are mature and capable
of germination in the right conditions seeds are nourished by the placenta in
the ovary (fruit). Somewhere on the seed
is the tiny opening where the pollen tube penetrated it and where the seed is
attached to the placenta. Consider it a seed belly button, there’s usually a
scar where it detaches from the placenta.
After
the seed detaches the little pore (hole) that’s left brings in oxygen and
releases carbon dioxide. The little
embryo is a living thing and all living things breathe and excrete. Remember
that as you pour those little peas into boiling water, you are killing plant
babies.
The
food a plant wraps around it’s little embryo is composed of fats, starches and
proteins. Its supposed to sustain the
embryo until it grows its own leaves and roots after germination. The food
storage areas are called cotyledons. We
find those food stores very helpful and tasty.
Its what we eat when we eat wheat, corn, oats, peanuts, beans and other
grains and legumes. It’s what we squeeze
to make canola and soy oil.
Here's your homework. In the picture below which items are fruits?
For
more information on seeds and various methods of germination please see this
article http://gardeninggrannysgardenpages.blogspot.com/p/seeds-germination.html
St. Patrick’s Cabbage salad
It’s
that time of the year where green foods and beverages are cheerfully served. If
you want a great salad to go with corned beef, try this recipe. Make this about an hour before you want to
serve it.
3
Tablespoons vinegar
3
Tablespoons sugar
½ cup
olive oil or sesame oil
½ cup
slivered almonds
2
Tablespoons sunflower seeds
1
package of Ramen noodles, chicken flavor
3 cups
of shredded green cabbage
4-5
good sized green onions, sliced thinly
Green
food color if in the mood
Remove
the seasoning packet from the Ramen noodles.
Mix
together the seasoning packet, sugar, vinegar and oil and set aside.
Boil
the noodles in a little water about 5 minutes, until soft. Drain and set aside.
Put the
almonds and sesame seeds on a cookie sheet and lightly brown them in the oven,
325 degrees about 10 minutes. Cool.
Toss
the cabbage, onions, almonds, sunflower seeds and noodles together.
If you
want a really green colored salad add a few drops of green food coloring to the
vinegar and oil mixture and stir well.
Pour
the oil mixture over the cabbage mixture and toss to blend well. Chill for 30 minutes or so before serving.
Book Review- The
Reason for Flowers- Their
History, Culture, Biology, and How They Change Our Lives
By Stephen Buchmann, publication date: July 21, 2015
If you like reading my free Master garden lessons you’ll
enjoy reading this book. The author studies pollinators and knows all the
fascinating little trysts pollinators have with flowers and explains how those
interactions heavily influence our civilization. The botany and function of flowers
is explained in detail but in an easy to read and understand way. You’ll be
learning lots of new things about flowers without even realizing you’re
learning.
Buchmann weaves an engrossing tale or several engrossing
tales, about the cut flower industry, the perfume industry, about spices and
foods and flowers in art. Wherever
flowers have been the author will take us there. The book is set up in sections, where one
reads about flowers from a different perspective in each section.
I loved the biology and botany sections, as well as the
cooking and perfume sections, but the flowers in art and literature sections
weren’t especially interesting to me, but hey, they may be favorites of
yours. You can easily skim through some
sections without losing context for the parts that deeply interest you.
The author brings up a fascinating idea to ponder as you
pull weeds this summer. Did we
domesticate plants and bend them to our desires or did they domesticate us and
make us their servants? This book is a great one for any gardeners library and
makes a good gift for a gardener also.
Kim Willis
“He who has a garden and
a library wants for nothing” ― Cicero
© Kim Willis - no parts of this
newsletter may be used without permission.
And So On….
Find Michigan garden events/classes
here:
(This
is the Lapeer County Gardeners facebook page)
An interesting Plant Id page you can
join on Facebook
Here’s a seed/plant sharing group you
can join on Facebook
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publish what I want. Contact me at KimWillis151@gmail.com
I write this because I
love to share with other gardeners some of the things I come across in my
research each week. It keeps me engaged with people and horticulture. It’s a
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