Seeds can fly – I kid you not! I have witnessed this force of nature on many occasions and admire the strategy of the plants that launch their precious projectiles toward a future life. OK, OK, I may have stretched the definition of fly a bit, so let’s just say sail instead. A variety of plants have evolved fruit that upon drying, explode open to expel their cargo into the air – flying, if you will.
I have an interest in propagating native plants, so collecting seeds is a must. One of my early interests was collecting seeds from Witch Hazel, a lovely small, understory tree. Seeds are held in small, semi-woody capsules that hold two, torpedo-shaped black seeds. I patiently watched to see these capsules open for me to collect those seeds, only to find capsules fully opened, with nothing inside.
I realized that I was dealing with a strategy of some plants to explosively expel seeds from a drying fruit. After seeds mature, the capsules or pods that hold them begin to dry, during which tension builds around a suture in the structure – a weak point that once triggered, violently reshapes the capsule. The loose seeds within fly through the air, I mean sail away from the parent plant, and hopefully to the ground and a safe place to germinate and grow.
So, back to the Witch Hazel, I decided that I was smarter than a plant and collected nearly dried capsules, thinking that I could place them in a jar in my air-conditioned house to dry, ensuring that the seeds would be easy to collect. Good plan, right? Except, I did not think it necessary to put a lid on the jar, instead leaving it on a windowsill in our den.
Now my wife Mary is a prayerful woman who loves to host small prayer groups in our home. And so it was that those capsules decided to explode in the middle of one of those sessions, sending little black seeds sailing about the room. Once Mary explained about her husband’s odd quest, the laughter ensued and we often recall the power of prayer to launch seeds.
But you do not need to witness the launching of seeds of many common plants you know. All you have to do is look for the misshaped pods that are left behind, most commonly on peas and other legumes. We of course love to collect bean pods before they dry out, explode, and expel their seeds, but they will if you let them. The process has a fancy name – explosive dehiscence or ballochory (ballistic dispersal). Once tension in the long pods is released, the two halves twist in opposite directions, flinging the dry seeds outward.
Those, dry, brown, twisted pieces hanging on your pea vine are what is left behind. I have been able to encourage a dry pod of Hairy Cowpea to explode by thumping it with my fingers or squeezing it a bit. Fun to do, but, as with Ralphie’s Mom in A Christmas Story, watch out so a seed doesn’t shoot your eye out.
Hope to see you in our great outdoors!
*Photos by Mark W. LaSalle
