Seed Saving Time: Legumes

Snow peas will cross with snow, snap and shell peas.By Jill Henderson – Show Me Oz 

If you’re planning on saving some of your own seeds this summer, the very best time to start is before a single seed goes in the ground.  In fact, your seed saving efforts should begin with that catalog you’ve been perusing all winter.  In addition to a myriad of valuable information such as germination times, growth characteristics, suggested planting dates and so on, many seed catalogs now list each vegetable’s Latin botanical name, as well.  You know the one I’m talking about…those two  little words written in italics and perched between parenthesis can mean the difference between seed saving success or seed saving failure.

Those of you who read my blog regularly already know that I am always blathering on about botanical names.  That’s because botanical names describe which plants have close family (and genetic) relationships and which ones don’t. They tell us which plants can cross pollinate one another, and which ones can’t.

Taking the time to learn how garden plants are related is probably the most important thing you will ever do as a seed saver. I highly recommend writing the botanical name on the front of every pack of seeds you buy (or save).  This will not only help you learn the names faster, but it also makes a good reference at planting time.

Now, if you are planning on saving seeds from any kind of bean or pea in your garden this year, you will want to know that all of the beans and peas we grow in our gardens belong to the Fabaceae, or Legume, family of plants (formerly known as Leguminosae).

sweet pea flowerThis sweet pea blossom shows the classic legume family flower structure.  Photo courtesy Morguefile.This is important to the seed saver because all members of the legume family have perfect, self-pollinating flowers.  Each individual flower contains both male and female reproductive organs and pollination generally occurs before the flower ever opens.  This is of great help to the seed saver because it greatly reduces the chance that the various varieties of legumes sharing the same species will cross-pollinate one another.

That being said, the fact that legumes have perfect self-pollinating flowers does not preclude the chance that insects will get into a flower before it fully opens.  In fact, large pollinators like bumblebees can physically force their way into closed flowers, while insects like bean beetles, which feed on pollen, chew their way in.  Both of these insects are vectors for cross pollination.  Because of this, legumes have a 35% chance of being cross pollinated by insects.  Admittedly, this is a slim possibility, but a possibility none-the-less.  And as a seed saver, you will want to reduce those odds in your favor by knowing which legumes have the ability to cross-pollinate.  The only way to do that is to know their botanical names.

So we already know that all legumes – all beans and peas – belong to the same family.  But it’s the botanical name that really tells the whole story.  The first part of that name represents the genus and the second, the species.  Take pole beans, for example. Their botanical name is Phaseolus vulgaris.  Phaseolus is the genus and vulgaris is the species.

There are many varieties of pole bean, but all of them are P. vulgaris, which means that they are so closely related that they can cross pollinate one another.  To make matters worse, all varieties of common pole and bush green beans, whether they are used as shell, snap or dry beans, are in fact Phaseolus vulgaris, which means that they have the ability to cross pollinate one another.  To help illustrate this point, here are just a few members of the very large legume family, see if you can determine which of these have the ability to cross pollinate.

Pole bean (Phaseolus vulgaris)
Bush bean (Phaseolus vulgaris)
Black bean (Phaseolus vulgaris)
Garbanzo or Chick Pea (Cicer arietinum)
Hyacinth bean (Dolichos lablab)
Soybean (Glycine max)
Copwpea or Crowderpea (Vigna unguiculata)
Mung bean (Vigna radiate)
Garden pea (Pisum sativum)
Edible-podded pea (Pisum sativum var. sativum)

Notice the first and last Latin name of each of these beans and peas.  Some, like the pole beans, bush beans and dry beans share the same exact family, genus (Phaseolus) and species (vulgaris).  This indicates that all common beans share an incredible amount of genetic similarities and are prone to cross pollination.  The same is true of cowpeas and mung beans: these plants share a common genus (Vigna), but not a common species name.  This should indicate that while these two plants are very closely related, they are not close enough to cross pollinate one another.

There are numerous varieties of crowder and cow peas, all of which can cross pollinate one another.In short, those plants that share the same genus have the potential to cross pollinate – but probably won’t.  But those that share the same genus and species, definitely will.   Those that don’t share either the genus or species can never cross pollinate.  So, if you are planning on planting several kinds of legumes in the same garden, you will definitely want to know which ones can cross pollinate, which ones can’t and which ones might.  Then all you have to do is find a way to ensure they don’t.

Since all legume family members have perfect self pollinating flowers, nature is already doing most of the work for you.  All you need to do to prevent cross pollination is to provide a little extra space between varieties of legumes that share the same species names.  This is called isolation.  For the hobbyist or home gardener, leaving as little as 4’-5’ between multiple varieties of the same species is often sufficient enough distance to prevent cross pollination, although the recommended distance for serious seed savers is around 20’.  And if you are growing a very rare or special family heirloom, you’ll need to  increase that distance to approximately 100 feet, just to be on the safe side.  Planting a tall or flowering crop in between two varieties of the same species is also a good way to achieve good isolation.

Another benefit of saving legumes is that they are natural inbreeders and do not readily suffer from the dreaded “inbreeding depression” – a sort of genetic bottleneck that occurs when too few seeds are saved from too few plants.

Lima beans will only cross with other lima beans.Inbreeding depression causes all kinds of problems that become increasingly evident as each generation of seeds is grown out.  Signs of inbreeding depression include low germination rates, loss of disease or pest resistance, overall plant vigor, and other distinguishing characteristic of that particular variety. While not strictly necessary with legumes, it is always good seedsmanship to save seeds from at least three or four different plants to help retain the natural genetic diversity that exists within each variety.

By planning now to save seed later, you can grow more varieties with the assurance that each and every one will retain their own unique characteristics for generations to come.

Happy seed saving!

© 2014 Jill Henderson  Feel free to share with a link back to the original article.


The Garden Seed Saving Guide by Jill HendersonIf you would like to learn more about how to save seed, check out my book,
The Garden Seed Saving Guide
Seed Saving for Everyone!

Save money, become more self-sufficient and avoid GMO’s by saving seeds!  This excellent resource for beginning and hobby seed savers takes you step-by-step through every aspect of saving your own seed in plain English.

Available in the Show Me Oz Bookstore
Look inside!


Jill Henderson is an artist, author, and the editor of Show Me Oz . Her books, The Healing Power of Kitchen Herbs, The Garden Seed Saving Guide and A Journey of Seasons can be found in the Show Me Oz Bookstore.  Jill is a contributing author for Acres USA and Llewellyn’s Herbal Almanac and her work has appeared in The Permaculture Activist and The Essential Herbal.


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6 responses to “Seed Saving Time: Legumes

  1. Pingback: Seed Saving: Beans & Peas | san diego seeds - saving and sharing heirloom seeds in san diego

  2. Nice post. I am an avid seed saver. Just planted our pole beans last night. My nephew Jake is a big help. Here’s a piece I wrote last year about why Greasy Grits.
    http://www.friendsdriftinn.com/gardening/jake-and-the-beanstalk-greasy-grits-heirloom-beans.html

  3. Pingback: Seed Saving Time: Peppers | Show Me Oz

  4. sorting seeds today and found this informative article:-) thank you:-)

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