Front Range Seed Analysts
1994 Seed Forum Volume 8 Number 2
Seeds of the Front Range:
Proboscidea: Devil's Claw or Unicorn Plant
by Annette Logan
Illus. by Cheryl Johnson (not available on this page yet)
Proboscidea spp. have big, distinctive seeds. Usually big seeds mean easy identifications. But I remember the first time I identified a Proboscidea seed. It wasn't in any of the standard seed plate/photograph reference books I always reach for first. I put the seed aside and came back to it from time to time during the day. I flipped aimlessly through the seed collection. "Bumpy watermelon," was all I could imagine. Barbara Atkins came to the rescue remembering its common name devil's claw. Another common name is unicorn plant. Searching the botany books for descriptions, we were further perplexed by the taxonomists' confusion over the scientific name.
Proboscidea is generally accepted as the current genus. Older floras may use Martynia. "Lumpers" place the genus in Pedaliaceae, while "splitters" place it in the family Martyniaceae.
Proboscidea is somewhat by itself in the web of plants. The nearest
relatives that you might know are sesame (also in Pedaliaceae) and catalpa
(Bignoniaceae). While the seeds of all three are radically different,
their flowers are remarkably similar. Hence the difficulty for seed
analysts who have never seen the seed before.
Look at Cheryl Johnson's drawing here and you would never guess to
check the part of the seed collection near sesame or catalpa!
Interest in Proboscidea has been rekindled by southwestern anthropologists studying the importance of devil's claw in Native American basketry and as food for tribes in the southwest. When the capsule dries and splits apart, the long, slender "proboscis" on the end becomes two excellent splints for basketry. These splints form the dark part of the pattern on many southwestern baskets.
The Seri Indians of Mexico, formerly ate part of the underground tuber of P. altheaefolia. Cowboys of the Sonoran desert used to feed the root to starving cattle. The seeds are edible and the immature fruit can be pickled. Several people have told me they remember, from childhood, painting the dried fruits and using them as Christmas ornaments.
It is clear that some varieties have been improved and changed by conscious selection over the centuries. In particular, the white seeded variety of P. parviflora has been chosen over the black seeded type for its longer splints on the fruit. Author Gary Nabhan in Gathering the Desert described just such a deliberate seed selection and plant rogueing by women in the chapter "Devil's Claw: Designing Baskets, Designing Plants."
Agronomists in recent times have focused on the plant's competition with many crops such as cotton where it achieves "weed" status. An analyst may also find it contaminating southwestern rangeland species' seed samples. However, analysts' exposure to devil's claw isn't limited to contaminants; several seed companies sell varieties of Proboscidea for home gardeners.
AOSA rules recommend embryo excision for germination. After removing
the thick outer seed coat, there is also a thin membrane that must be pricked
or carefully peeled away. It is easier to do this after the seed
has imbibed for a few hours. Another option is clipping the cotyledon
end.
We have printed Cheryl Johnson's drawing here with a laser copier
to keep as much detail as possible. (not yet available here on the web)