Subfamily: Faboideae.
Phylogenetic Number: 3.21.03.
Tribe: Trifolieae.
Species Studied - Species in Genus: 16 studied; 19 in genus.
Fruit: A legume; unilocular; 0.15–0.8 cm long; 0.15–0.45 cm wide; 0.12–0.4 cm thick; length less than twice as long as width; with deciduous androecial sheath; with deciduous corolla; with persistent calyx, or deciduous calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; asymmetrical, or symmetrical; circular, or lanceolate, or oblong, or obovate, or ovate; with both sutures parallelly curved; not inflated; compressed, or terete; without beak; short tapered at apex, or rounded at apex; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit (slightly); short tapered at base, or rounded at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; membranous, or chartaceous, or fragile, thinner than chartaceous, like Trifolium; seed chambers externally visible; margin not constricted; margin without sulcus; margin plain; wing(s) absent; nonstipitate; indehiscent, or with all layers dehiscing (M. altissimus J.L. Thuillier); splitting along suture(s). Dehiscence of valves along 1 suture; medial and up and down; passive. Replum invisible. Epicarp dull; monochrome; black, or brown, or tan; with surface texture uniform; glabrous, or pubescent and indurate; with hairs appressed; with 1 type of pubescence; with pubescence gray; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; veined, or not veined; obliquely veined relative to fruit length, or reticulately veined; not tuberculate; concentric whorls like a fingerprint, or ribbed, or wrinkled; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; dull; opaque; monochrome; brown, or tan; smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to epicarp; without wings; entire. Seed(s) 1, or 2; length parallel with fruit length; neither overlapping nor touching, or touching; in 1 series. Funiculus 0.1–0.8 mm long; of 1 length only; filiform; straight, or curved. Aril absent.
Seed: 1.5–4.5 mm long; 1–3 mm wide; 1–2.2 mm thick; not overgrown; not angular, or angular (somewhat); asymmetrical; circular, or elliptic, or mitaform, or reniform; compressed; with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; glossy, or dull; not modified by a bloom; colored; monochrome, or mottled, or streaked; with frequent mottles; with frequent streaks; brown (and yellowish, greenish), or green (and yellowish), or tan, or yellow; with purple overlay; glabrous; smooth, or not smooth; with elevated features; shagreen, or warty; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; partially concealed; concealed by funicular remnant; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform, or larger than punctiform; with curved outline, or angular outline; circular; triangular; between cotyledon and radicle lobe; flush; not within corona, halo, or rim. Lens discernible; 0.6 mm long; with margins straight, or curved; oblong; oblong; not in groove of raphe; confluent with hilum (at least discolor area); mounded; dissimilar color from testa; darker than testa; brown; not within corona, halo, or rim. Endosperm present; thick; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to embryo. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded, or with both folded; not sufficiently folded for inner face to touch itself (essentially cotyledons longer than testa); portions of inner folded face equal; margin entire 180 degrees from base of radicle; similar at apex; not concealing radicle; entire over radicle, or notched at radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; tan; inner face flat; glabrous on inner face. Embryonic axis deflexed; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; bulbose; deflexed and parallel to cotyledon length; centered between cotyledons; 1/2 to nearly length of cotyledons. Plumule rudimentary, or moderately developed; glabrous.
Stevenson (1969) reviewed Melilotus, recognized 18 species, and illustrated its fruits. Jha and Pandey (1989) studied the seeds, especially the testae, of 11 species of Melilotus. They concluded that the testa coat ornamentation for a species is characteristic "and of great importance in specific diagnosis of a seed." Isely (1954) provided flower-fruit keys to the 20 species of Melilotus. Voronchikhin and Bazilevskaya (1974) described fruits and seeds of the nine species of Melilotus in the former U.S.S.R. Small (1989) noted that M. bicolor P.E. Boissier & B. Balansa may perhaps be better placed in Trigonella (21.04). Presently our number of species includes M. bicolor and is the count in Small, not the ca. 20 species of Heyn (1981). We are not adopting Small's selection of "a" to end species names currently ending in "us" in Wiersema et al. (1990). Schulz (1901:667) noted that the two seeds in a pod may be different colored: one light yellowish brown and the other dark reddish brown.
Tribe Trifolieae
Endo and Ohashi (1997) have proposed, after a cladistic analysis using morphological characters, including internal seed morphology, that Cicereae (20) and Fabeae (19) formed a monophyetic group whose sister group is Trifolieae. Ononis and Parochetus (21.02) "are not nearly as closely related to the remaining four genera as the latter are to each other, and indeed that the two genera are not at all closely related to each other (or so far as I know to anything else)" (E. Small, pers. comm. 1997). Butler (1996) presented a table with eight seed characteristics of 14 Medicago (21.05) spp., seven Melilotus (21.03) spp., 25 Trifolium (21.06) spp., 11 Trigonella (21.04) spp., and two Ononis spp. as an aid for their identification in archaeological sites.
Authors: J.H. Kirkbride, Jr., C.R. Gunn, A.L. Weitzman, M.J. Dallwitz, K.R. Thiele
Content last updated April 2003
Released April 2024 on idtools.org
