Is that a Mucuna or a Dioclea?

This page is intended to provide information to help distinguish between the genera
Mucuna, the "Hamburger Beans" and Dioclea, the "Sea Purses".

This page is presently under construction.
Check back to watch it grow ...or to contribute to it!   Email me:

To show variety and variability, each section will (eventually) link to a page dedicated to examples;
i.e., the section on flowers will link to a page of flowers, the section on seeds will link to a page of seeds, etc.

Quick Index:   Seeds | Leaves | Flowers | Pods | Taxonomy

The Seeds

With this website's focus on Sea-Beans, the seeds of Mucuna and Dioclea would seem to be of most interest.
Typically, the seed is the only thing that is available to the collector, i.e., the "beaner".

General characteristics are emphasized, but be advised that great variability can occur!

Comparison and contrast of typical seed SHAPE.
In this section, pay no attention to color or coloration pattern!
Dioclea reflexa, Sea Purse Notes Mucuna sloanei, Brown Hamburger Bean
Dioclea reflexa
Side View
Note the flat "top" of the seed, indicative of a purse shape, giving it the common name: Sea Purse. In species of Mucuna, you are more likely to see this region more rounded. Note also the rippled surface of Dioclea and the dimpled surface of the Mucuna example.
Mucuna sloanei
Dioclea reflexa
Hilum View
Is the hilum narrow or thick, with respect to the total thickness of the seed? Also, in Dioclea, the hilum "edge" of the seed is typically protruding, making a sharper edge than the more flattened hilum edge of Mucuna spp. In these examples (i.e., not always!), Mucuna is more inflated.
Mucuna sloanei
Dioclea reflexa
Non-Hilum View
Examining the "top" of the seed is helpful in that species of Dioclea will lack a "smiley" at the end of the hilum, while this is quite evident in most Mucuna spp.
References and Links
  • Sullivan, G. and J. Williams. 2008. Smiley. Part I -- Mucuna vs. Dioclea -- No Problema! The Drifting Seed 14(1):2-4.
  • Definition of hilum. Courtesy of Kew Royal Botanic Gardens.

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    The Leaves

    Comparison and contrast of typical leaves...     their shape, veination, and adornment.
    Dioclea reflexa, Sea Purse Notes Mucuna sloanei, Brown Hamburger Bean
    Dioclea reflexa
    Young Leaves
    Both Dioclea and Mucuna exhibit three "leaflets" to each "leaf". Those for Dioclea will typically all be in the same plane, while those for species of Mucuna will have its unpaird leaf pointed upward, out of the plane of the paired leaves. This is much more evident in mature leaves viewed from the side.

    Note the very hairy nature of the young leaves and stem for Dioclea. Although the Mucuna leaves do have hairs, the extent (in this case) is much less than is present in Dioclea.

    Mucuna sloanei

    The Encyclopedia of Life (EOL) web page has a photo of leaves of Dioclea reflexa.
    Mature Leaves
    Leaflets: Both Dioclea and Mucuna exhibit three "leaflets" to each "leaf".

    Venation: The veins of the paird leaflets in Dioclea and Mucuna is quite distinct. The venation in the paired leaflets of Mucuna are unequal, with the portion of the leaflet on one side of the main vein much being larger than the other, creating a "lobed" appearance.

    Hairs: The mature leaves of Dioclea are more hairy than those of Mucuna. Examine the leaves at an angle, in the right light, and the hairs will be quite evident.
    Mucuna sloanei
    Mucuna sloanei

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    The Flowers

    Comparison and contrast of typical flowers.
    Dioclea, Sea Purses Notes Mucuna, Hamburger Beans
    Waiting for plants to sprout and grow to take a photo of the flowers.

    Meanwhile, this web page has a photo of a spike of flowers of Dioclea reflexa.

    See also this web page for Dioclea hexandra.
    Flowers of Dioclea occur on an upright "spike", while flowers of Mucuna hang downward on a peduncle and are arrayed in a "umbelliform cluster", or a "pseudoraceme cluster ". Mucuna sloanei
    Umbelliform cluster of
    Mucuna sloanei flowers.

    Mucuna urens
    Pseudoracemose cluster of
    Mucuna urens flowers.
    Photo: Gina Reed

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    The Pods

    "Pod" is the term which refers to the fruit of legumes.
    Dioclea reflexa, Sea Purse Notes Mucuna sloanei, Brown Hamburger Bean
    Waiting for plants to sprout and grow to take a photo of the pods.

    Meanwhile, this "Wayne's Word" web page has a photo of a pod of Dioclea wilsonii and Dioclea reflexa.
    (scroll way down the page)
    The seed pods of Mucuna species typically have stinging hairs (called trichomes), while the seed pods of Dioclea species typically do not. Mucuna sloanei

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    The science behind the names and classification.

    Classifications group similar organisms and seem to always be in a state of flux or revision. Presently, both of these genera, Dioclea and Mucuna, are considered to be in the family: Fabaceae     ...previously considered to be called the Leguminosae (s.l.) or Papilionaceae (s.s.). Plants in this third largest family of land plants are commonly known as a legumes, peas or beans. Faba, in Latin, means "bean". The "type species" (below) is that species selected to exemplify the characteristics of those plants within the Genus.
    Dioclea Hook f. Mucuna Adans.
    The name after the genus: You may see this genus presented as "Dioclea Hook f." or "Dioclea HBK" or "Dioclea (Hook f.) C. Wright" or "Dioclea Kunth".

    This is the name of the person who first described the species; if that name is in parenthesis, the species was first named and placed within a genus other than the one presently shown.

    Etymology: Named for Diocles, considered by the ancient Greeks to be second only to Hippocrates in his knowledge of Plants.

    Lectotype species: Dioclea sericea HBK. A "lectotype" is one that is designated after the genus was originally described, because the "type" species was never established or was invalidly designated.
    The name after the genus: You may see this genus presented as "Mucuna Adans."

    Mucuna is a "conserved" name. The original spelling was Macuna but because Mucuna had become so embedded in popular usage, it was conserved and officially designated as the valid spelling of the genus.

    Etymology: From mucunan, the name given these plants by the Tupis, South American Indians of the Amazon valleys of Brazil.

    Type species: Mucuna urens (L.) DC.

    Generic characteristics of Dioclea and Mucuna
    Information taken and modified from:   Allen, O.N. and E.K. Allen. 1981.
    The Leguminosae. A Source Book of Characteristics, Uses, and Nodulation.
    University of Wisconsin Press; 812 pp.

    Characteristics of Dioclea

    30-50 species.
    Vines, woody or shrubby, tall, climbing.

    Leaves pinnate 3-foliate; stiples sebaceous; stipules sometimes present.

    Flowers large, many, violet, blue, or white, in clusters on sessile or stalked nodes on axillary, elongated racemes; bracts narrow; bracteoles orbicular, membraneous; calyx campanulate, silky haired-inside; lobes 4 or 5, upper 2 united, lowest lobe longest; standard ovate, reflexed, with 2 inflexed, basal auricles; wings free, oblong; keel blunt, straight, or incurved, short; stamens 10, pseudo-monadelphous, vexillary stamen free only at the base; anthers all fertile or alternate ones small, abortive; ovary subsessile; ovules 2-many; style incurved, usually not bearded, dilated above; stigma terminal, truncate.

    Pod linear-oblong, compressed or turgid, leathery, 2-valved, both sutures narrow-winged or upper one thickened, dehiscent or indehiscent.

    Seeds usually globose with linear hilum.

    Characteristics of Mucuna

    100 to 150 species.
    Herbs, vines, rarely shrubs, climbing, woody, tall, rarely short and erect.

    Leaves pinnate 3-foliate, usually large; leaflets asymmetric, often oblique-ovate, usually hairy, aciculate; stiples usually present; stipules small, usually caducous.

    Flowers large, showy, purple, orange, scarlet, red, or yellowish fascicled-racemose on axillary peduncles or subcymose at the apex of the peduncle; bracts and bracteoles small, caducous,; calyx often hairy, bilabiate; lobes 5 ovate, upper lip bilobed, lower lip trilled, longer; standard sessile, ovate-elliptic, folded inward eared at the base, ears often upturned. subequal to the wings; wings oblong-ovate, incurved, sessile, eared, often adherent to the keel; keel sessile, linear-oblong, incurved or beaked, often longer than and joined to the wings; stamens 10, diadelphous; anthers unequal, alternately longer and basifixed, shorter and dorsifixed, bearded; ovary sessile, few-ovules, villous, surrounded by a poorly developed, usually basal, cupular to lobular disk; style linear, filiform; stigma small, capitate, terminal.

    Pod thick, ovate to oblong, often covered with brown, stinging hairs, 2-valved, septate within.

    Seeds 1-10, large, rounded, discoid with hilum more or less one half the circumference or smaller ovoid, with a short, raised hilum.

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