Collecting Native Plant Propagules

Timing

Contents


Learning Objectives

Narrative

Acquiring Knowledge and keeping Records
Keeping a record of exactly where a plant grows, when it flowers and produces seed, as well as a map of where you will be planting it later are all of equal importance and simply stated there is no substitute for good habits in planning and keeping your records up to date.
It should be emphasized that the importance of keeping records should extend to both success and failure. We should all be happy to only make new mistakes instead of the same old ones over and over again, and finding out where you went wrong will be far easer if you wrote everything down when it was happening rather then attempting to recall just where that seed came from two years ago and how you stored it.
Seeds
Familiarity with the phenology, the life cycle of the plant you collect seed from, is important because it is necessary to know when flowering, seed formation and seed maturity will occur. Understanding dispersal mechanisms of the species and the effects of environmental changes, such as bird migration, insects, encroachment and the weather, is also helpful. Experience, time and your own records are the most important factors to consider when collecting seeds. First, observe the plants; watch and record the life and growth cycle of each species. This is important because it is the best way to find out when plants typically bloom and when the seeds are generally ready for collection as well as planting. Also, it will help to understand the most important part of seed collection, timing.
Timing of harvest is important because if seeds are collected too early, the seeds will be immature and have low seed viability. If seeds are collected too late, they can dehisce quickly and be lost.
Seeds that are collected after dispersal are usually of low quality and are potentially costly and time consuming to clean. Other aspects to consider are that seeds seldom ripen uniformly over the same flower stalk. Prolonged flowering and different stages of seed maturity limit uniform seed collection so your collecting should take place over as long a time period as possible. Lengthy observation and experience are the best resource - until you have it your self, dragging someone with you with lots of previous experience is always the best way to determine when particular seed species should be collected.

No matter what kind of native seeds you intend to collect, you must keep a constant watch on the plants involved. Even though a plant may produce flowers there is no guarantee that you will be able to collect the seeds. Some plants may not produce seeds due to poor pollination. Steady rains, unseasonable temperatures, and strong winds can affect the activity of bees and other insects that pollinate natives. Wildlife such as squirrels, mice, voles, chipmunks, insects and birds are all waiting to collect tasty seed using their own methods as well. Ants are especially problematic when it comes to collecting seeds and if especially troublesome, it may be necessary to wrap the green seed pods in tiny cheesecloth bags while the seeds ripen on the plants.

If the seeds you are collecting come from a plant that has seeds that ripen in pods they should be collected just as the pods are beginning to open and just before they fall to the ground. When seeds are on the ground, the likelihood of disease and insect infestation is greatly increased. Also some seeds loose viability (ability to germinate) soon after they are ripe and should not be collected from the ground. Collecting the entire pod is usually the best method because this allows the seed to continue ripening in the pod as it dries. Plants that dehisce (break open and dispel seeds) can be contained by placing a paper sack over the seed head and closing the open end with a twist tie. Exposure to light and air will allow seed ripening as the bag collects the seed. This method allows for collection once at the end of seed maturation. Care should be taken as it is not beyond the character of some birds, squirrels and insects to find that your bags contain some tasty treats!

Assuming you outsmart the critters, you still must check the plants frequently for maturity. As a general rule, most seeds start to ripen when the pods or capsules change color or when the seed heads start to open. Seeds that are mature are often dark in color, firm and dry. Fleshy seeds often turn color as they mature and become ripe. These seeds should be collected as they are changing color. Berries or fleshy fruits should be collected when they are obviously ripe. Some seeds are ripe when the seeds are still green, but a careful touch with a finger will loosen them.

While timing your seed collection should be based primarily on observation and good record keeping, other means of determining seed maturity exist. Using the moisture content of the seeds is possible. Immature seeds have a moisture content of approximately 60%; whereas mature seeds has a moisture content closer to 10%. There are some high-tech methods to help with this from the Karl Fischer reagent test which must be performed by a chemist, to electronic sensors and infrared balances. Seed maturity-moisture content curves have been determined for a number of species and can be used as a guide to collecting seeds. The basic concept of seed maturity increasing as moisture content decreases can be used as helpful guide. For our purposes we use the bite test.
The bite test: This tried and true low-tech method is to simply take a seed and carefully bite it, if it feels rubbery the moisture content is too high and you need to collect at a later date.
Experimenting with germination tests is also helpful in determining at what stage seeds can be collected. But this is beyond the purview of this workshop.

Wildflowers that produce many seed heads or capsules on a single stalk like Penstemon will ripen their seeds over a period of weeks. You can pick the ripe ones every day, or you can cut off the entire stalks when the first few seed heads or capsules are fully ripe.

Seeds should be collected when they are thoroughly dry, if possible. Moisture from rain or dew can ruin seeds very quickly.

Exercises

  1. Pods. California poppies have a long blooming period, so at any given time from spring to fall, you may find seed pods in various states of maturity. Pick a variety and open them up to observe the development of the seeds. Do some pop open when you handle them? Determine which pods are at the appropriate stage for collecting. How would you describe them?
  2. Bite Test. Gather a variety of seeds at various states of maturity and practice the bite test. You can try it on your California poppy seeds of the previous exercise, but the seeds are very small and hard to handle. Start with seeds where you are fairly confident of their level of maturity to get the feeling, then experiment with others where you are not sure. Be sure to avoid seeds of poisonous plants, such as
    • poison hemlock and other members of the carrot family,
    • oleander,
    • members of the nightshade family,
    • cotoneaster,
    • cocklebur,
    • california buckeye,
    • mistletoe.

References


 
The content of the page was last modified 2008-05-06