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Posts Tagged ‘Native plant seed genetics’

When I was a child growing up on the edge of a white (Quercus garryanna) oak forest in Oregon I loved to collect the wild seeds of native plants. I was attracted to their great beauty, unusual design, and uniqueness. I was fascinated by their shapes, sizes, colors and even smells. They were my special treasures.  I kept a collection of wild seeds in a tin box under my bed away from the prying eyes of my many siblings.  I would often take the box out and pour over my many wild seed “treasures”.

I spent hours collecting, observing, and drawing pictures of the seeds. I had special names for the seeds: “whirligigs” (the samara or winged seed pod of the Acer or Maple tree family),” wishes” (the multi-seed pod of the dandelion),” hooksters” (the hooked seed of the Cleavers), and “boings” (the seed pod of the wild pea or Vetch).

I asked my father, who was a very amazing gardener, why my seeds looked so much different than the seeds we planted in our garden.  He told me that the seeds planted in the garden had been changed by man over many years.  They were hybrids of once wild plants.  He told me that the seed I collected was wild seed. Seed that only nature had touched.

I scanned the Book of Knowledge book set that was in our family’s library looking for information about wild plants and seeds.  I had many questions.  I wanted to know why some seed had tails and seemed to fly through the air; some oozed fluids and were sheathed in pockets of paper-like plant material. Still others were very hard to touch because they were sheathed in very hard outer shells.  I found seed that dropped to the ground and burrowed itself into the earth. Other seed attached itself to animals or my pant leg and later dropped far away from the mother plant. Some seeds used streams and rivers to move through the forest and still others catapulted themselves through the air.

The shapes of the seeds fascinated me. They were not only small, oval or round like the garden seeds, they took many shapes and sizes.  Some seeds were encased in berries; others were encased in cones or grew in long clusters. Some were round, some were square and a large number were geometrically shaped like small geodesic domes.  Every seed was unique and held a mystery within it. Every seed had adapted so it could survive a more or less competitive environment. I learned that plants disperse their seeds because they do not want new plants nearby competing for water, light and nutrients.  The fruits or pods that contain the seeds have adapted to different dispersal methods.  For instance, the acorn of the White Oak has a fruit that looks like a seed, but the outside of the acorn has a tough wall to protect the seed within. When the acorn falls to the ground it rolls away from the parent plant.  The acorn is very attractive to animals.  The squirrel will carry the acorn away and bury it. How convenient that the squirrel “plants” the acorn in the ground.

Some seeds develop coats of paper thin material – capsules and pods. As the pod membrane dries it creates tension and finally the pod will pop open- throwing the seed in all directions (Sweet Vetch and other pea family plants). The paper-like pod is also easily dispersed in the wind.  Some seeds have hooks – much like Velcro that allows the seeds to attach themselves to animals and people to be carried away.

In fact the inventor of Velcro Swiss engineer, Georges de Mestra was said to have studied the mechanism of a common burr to come up with the idea for his amazing invention.

One year I took half my collection and planted the seeds in a small bed of loose soil.  Very little of it germinated. Only some wild grasses came up. None of the wildflowers grew. I was so disappointed.

As always my dad patiently answered my many questions. He told me that wild things are special and unique and cannot easily be captured. He said most die in captivity and cautioned me not to catch the wild frogs or salamanders or try and hatch the pheasant eggs I found in the orchard. My father told me that wild plants also needed special care and in order to germinate the seeds I would have to learn everything I could about the plant first.  He said some seeds have special needs like a long cold spell, or fire or being eaten by a bird.  My father told me that unless we protect the wild plants we may lose our food plants, our forests, our water and our air. He said that all our food and flower plants were hybrids of wild plants. He said that hybrids become harder to grow over time and have to be grown again from wild stock at some time. If the wild stock disappears, so will our easy to grow food sources.  My father had great respect for wild plants. He taught me how to forage for berries and other food.  And he told me the names of the native and wild plants.  It was my father who told me that in the past First Peoples everywhere used wild native plants for everything in their lives.

Because of the general lack of training in biological/botanical training in the schools at that time I decided to learn everything I could on my own through books.  I spent hours in the library reading about plants and learning their mysteries.

I spent a good portion of my life trying to learn about native plants and how to propagate them through direct observation.  Some native plants must be grown from seed and have very peculiar growing habits. In nature only a small fraction of the seeds of plants succeed in germinating and growing to maturity because of the many hazards encountered. Each plant has a peculiar way of making sure it’s seeds will be distributed to safe environments. My own observations from gardening and also working with native plants have taught me that wild seeds flourish in their wild habitat and contribute to a plant community that is exquisite and dynamic. One has only to visit an old growth forest and experience the diversity of life, the mycelium and the healthy web of life to know that wild plants know something we do not yet understand. This is why so many fragile native plants do not do well in people’s yards. To successfully propagate native plants one must understand and create a replica of the environment that the plant came from.

As we move native plants back into our yards, cities and towns we will need to make sure there is enough diversity of plants and we need to keep protecting the wild areas where the plants flourish.

In his essay on the need for diversity in plant and seed life, D.A Albert proposes that creating small areas of plant repositories (plant zoo) can create fragmentation leading to the destruction of whole plant species.

“Habitat destruction and fragmentation by development interrupts normal plant dispersal and gene exchange. In extreme cases, isolation creates highly inbred populations which can have a number of deleterious effects. Highly inbred populations may not have the genetic variability “on the warehouse shelves” to adapt to change. Inbreeding poses additional problems for self-incompatible species. These species can become so inbred that cross pollination between “different” individuals is no longer possible, rendering the population unable to produce viable seed.” (Albert)

THE SPARK OF LIFE

One of the greatest biological mysteries for me when studying seed is how is it that life is generated from a seed?  At what point in its growth do seed grow or die. Where does that spark of life come from?  I was told in my biology classes that that the spark of life starts in the DNA and biochemical material of a plant.  But I also know that scientists do not know where the spark of life comes from. Scientists only have theories and hypothesis to work with and cannot fully prove where the spark begins.

In just the right conditions, the seed will germinate.  Growth occurring as a result sees new life in no obvious way resembling the origin from which it springs. Biochemical reactions cannot explain where the spark comes from. It is truly a great mystery. We are just now beginning to understand that toxins and radiation can destroy that spark or mutate it into a plant that has no chance of survival. We must learn to protect the “spark” of life.

EACH PLANT HAS ITS OWN ENVIRONMENTAL NEEDS

You cannot generalize about any wild plant-or seed for that matter. Each has its own environmental needs. Study, observation and trial and error are the tools of a good naturalist.

For instance many wild plants do not produce seed until fall and few can be expected to germinate within a few days like garden seeds. Some seeds may not germinate for years and many need cold to prepare them for germination.

Seeds from many wild flowers have embryos that are immature when they are shed from the parent plant. An after-ripening period is necessary to overcome the dormancy of such seeds before germination can take place. (Taylor and Hamblin)

Wild seeds may need a cold moist repository for periods from one month to a year according to species (cold stratification). Some seeds have very hard outer coats that require almost two years of stratification. Plants that need this cold stratification include Pacific madrone (Arbutus menziesil).

Some seeds must pass through the gut of animal in order to germinate.  Placing the seeds in a container of hot water can mimic this process.  Here are some directions for this process presented by Washington State University extension service.

“HOT WATER (mimics passage through a stomach or heat from a fire): Boil 3-6 cups of water for every cup of seeds. Don’t use an aluminum pan or softened water, as either might introduce chemicals toxic to seeds. Turn off the heat when it reaches boiling, and let the water cool for a minute or two. Pour the seeds into the water and let them sit at room temperature for 24 hours. Seeds may still need to overwinter or be cold-stratified before they will sprout. Try this technique with Hairy Manzanita (Arctostaphylos Columbian), Kinnikinnick or Common Bearberry, (Arctostaphylos uva-ursi), or Snow Brush (Ceanothus velutinus).”

For more tips on how to germinate native plant seeds check out this website put together by the Washington State University extension service.

http://gardening.wsu.edu/text/nvgrowng.htm

THE STRUCTURE OF SEEDS

Fully developed seeds usually consist of an embryo – a tiny plant with a shoot (plumule) and a root (radicle) together with seed leaves (cotyledons) – that is surrounded by a mass of food (endosperm).

Angiosperms

Flowering plants (angiosperms) are divided into two groups.

Monocotyledons have one seed leaf usually parallel veins on leaves, indistinguishable petals and sepals in multiples of three and non woody stems.

The dicotyledons, also known as dicots, have two seed leaves, net-like veins on the leaves, often small green sepals, petals usually in multiples of four or five and thicker stems that may have woody tissue, formed by the (cambium).

Gymnosperms

The seeds of gymnosperms are “naked” or only partly enclosed by tissues of the parent plant. An example would be a conifer cone.  Conifer cone seeds are wind pollinated and seeds form on the scales of the female cones.

Spores are not seeds. Plants such as mosses, liver worts, ferns, club mosses and horse tails reproduce by spores. A spore may look like a seed but is asexual and develops male and female sex organs independently from the plant that bore it.

REFERENCES

*Albert, D.A., 1995. Regional Landscape Ecosystems of Michigan, Minnesota and Wisconsin: A Working Map and Classification. USDA Forest Service, North Central Forest Experiment Station. General Technical Report NC-178.Viewed on the web on December 1, 2011 http://www.wildtypeplants.com/gentalk.html

Phillips, Harry R., Growing and Propagating Wild Flowers, An easy-to-use guide for all gardeners, The University of North Carolina Press. Available from NJ Audubon stores and many other retailers.

Taylor, Kathryn S. and Hamblin, Stephen, (1963) Handbook of Wild Flower Cultivation: a guide to wild flower cultivation in the home garden, p.14 The Macmillan Company, NY

VOCABULARY

hybrid n. Genetics . The offspring of genetically dissimilar parents or stock, especially the offspring produced by breeding plants or animals of.

rad·i·cle/ˈradikəl/ – The part of a plant embryo that develops into the primary root.  A root like subdivision of a nerve or vein.

A samara is a type of fruit in which a flattened wing of fibrous, papery tissue develops from the ovary wall. A samara is a simple dry fruit and indehiscent (not opening along a seam). It is a winged achene. The shape of a samara enables the wind to carry the seed farther away than regular seeds from the parent tree as in the maples (genus Acer) and ashes (genus Fraxinus).

Scarify– Scarification means scratching or cracking the hard outer coat of a seed to help it germinate. Some seeds  have outer shells that are extremely hard and don’t allow water through. This is one way a seed stays dormant in the fall and winter, until growing conditions improve.

WEB RESOURCES

Here is a link to a wonderful website put together by Washington State University extension service on propagating native plants from seed. http://gardening.wsu.edu/text/nvgrowng.htm

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