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Mucuna spp. MAIN PAGE

Mucuna elliptica (Ruiz & Pavon) DC., 1825
The Thick-Banded Mucuna

See also: the Mucuna elliptica page in the "Sea-Bean Guide"
See also: Photos of Mucuna elliptica Seed Pods!
See also: images of Mucuna elliptica stipels and other leaflet terminology, click here.

This species was previously called Mucuna fawcettii, but was determined by Tania Moura, et al, to be conspecific with Mucuna elliptica.

Moura, T. M., G.P. Lewis, V. F. Mansano and A. M. G. A. Tozzi. 2014. Taxonomic Studies in Mucuna Adans.
(Legunminosae - Papilionoideae) from Peru. Systematic Botany 39(3):884-896.

Because Mucuna elliptica was published in 1825, prior to Mucuna fawcettii in 1908, the earlier published work takes precedence. The common name of "Thick-Banded Mucuna" or "Thick-Banded Hamburger Bean" is applied to this species due to the thickness (height) of the black hilum surrounding much of the periphery of the large seed... i.e., large for Mucuna species.

Mucuna fawcettii was once considered to be both endemic to Jamaica and also extinct from Jamaica. This situation could not be true if we were occasionally finding fresh seeds stranded on beaches of the Gulf of Mexico, Florida and elsewhere. My two purchases of seeds from the Amazon region of Peru yielded these seeds on both occasions. They were growing in the jungles of the Pulcallpa region, along the Ucayali River, a major tributary to the Amazon River! Evidently, the seeds fall to the jungle floor, wash into the Ucayali River, are carried to the Amazon River, float downstream to the mouth of the Amazon, and out to the Atlantic Ocean where currents carry them to their beach destinations.

One of these purchased (non-drifted) seeds was planted by Gina Reed and her results are shown in the Sea-Bean Guide. Gina's seed sprouted, grew, and produced flowers. However, no pods ever developed. I later planted a seed; it sprouted, grew, and produced two inflorescences (clusters) of flowers. As the flowers matured, I noticed that they were not opening on their own... and thus no pollination would occur, and thus no pods would be generated. Therefore, I manually opened all of the flowers and pollinated each flower myself! Sadly, this effort was "fruitless" ...i.e., no fuit (pod) was produced by any of the flowers.

The photos shown below document efforts to better understand the life cycle of Mucuna elliptica.

Non-drifted seeds direct from the Amazon region of Peru

The hilum is very thick, hence its name: Thick-Banded Mucuna

Young leaves

Mature leaf (Note: 3 "leaflets" = 1 "leaf")

Note the offset midrib of paired leaflets, characteristic of Mucuna

Very young bud

Maturing bud, almost ready to open

Young flowers emerging from the bud

Immature flowers, about 12mm long

Note fine hairs on the young flowers

Hairy flowers growing downward

Downward pointing flower will eventually twist and point upward!

Young flowers in the process of twisting upward

With more growth, the flowers have finished twisting upward
Flowers now open upward, affecting whatever implements pollination!
The pistil will now emerge above the stamens and pollen.

Side view of inflorescence (flower cluster)

Inflorescence seen from above

The brown calyx is diagnostic, distinguishing one Mucuna from another

Stipels, photographed from a pressed and dried leaf.
The presence of stipels (red arrows) is a key characteristic of M. elliptica,
distinguishing it from Mucuna pseudoelliptica which lacks stipels.
For images of stipels and other leaflet terminology, click here.

Inflorescences have several bracts that persist when in flower.
The red arrow is pointing to one of the bracts.

Mucuna pseudoelliptica has bracts which are caducous (they fall off).

	abaxial leaflet hairs	bracts	stipels
*Mucuna elliptica*	dense	persistent	present
*Mucuna pseudoelliptica*	sparse	caducous	absent

TWO characteristics (stipels present and persistent bracts) indicate that the plant on this page MAY be Mucuna elliptica.
However, the abaxial surface of the leaflets have (what I believe to be) sparse hairs, indicative of Mucuna pseudoelliptica.
Thus, I'm not sure what ID to place on this plant.
On another, young plant of this species (growing July 2014), the abaxial leaflet hairs seem dense on young (60 mm) leaflets
and quite sparse on older (180 mm) leaflets.
Also, although the bracts are present and persistent when the above photos were taken,
I do not know if they were caducous (fell off) later in development.
I suspect that the presence/absence character of stipels is a stronger indicator than the subjective determination of abaxial hair density...
therefore, I suspect that the species shown here is M. elliptica.

Copmpare this situation with another plant of this species, which has caducous bracts and (what is believed to be) sparse abaxial leaflet hairs.
Unfortunately, this other plant no longer exists and cannot be checked for stipels and existing leaf photos do not show the area where stipels would be.

Mature flower, but still unopened, with stamens and pistil not exposed

Tip of opened flower, exposing a stamen (with pollen) and the pistil
Flowers NEVER opened on their own to expose the stamens and pistil. Each had to be manually opened and pollinated. In nature, both the flower opening and pollination MAY be done by nectar-feeding bats (which don't exist in Florida) or by birds, some of which may go after insects associated with the flowers, inadvertently opening the flower and getting pollen all over their heads! Such Mucuna flowers open with such force they are referred to as "explosive" flowers.

Dissected flower

Opened flower, to expose stamens and pistil
Note 1 stamen separated from others... a condition called "diadelphous"

Closeup of stamens, with white pistil slightly out of focus

Calyx comparisons: Mucuna elliptica (left), Mucuna sp. #001 (center), Mucuna sloanei (right)

Flower size comparison: Mucuna elliptica (left, 95 mm), Mucuna sp. #001 (center), Mucuna sloanei (right, 65 mm)