Subfamily: Faboideae.
Phylogenetic Number: 3.21.05.
Tribe: Trifolieae.
Species Studied - Species in Genus: 83 studied; 86 in genus.
Fruit: A legume, or a nutlet; unilocular; 0.2–10 cm long; 0.1–1 cm wide; 0.2–1.5 cm thick; 2–9 times longer than wide, or more than 9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx; with calyx shorter than fruit; with orifice formed by curving of fruit or fruit segments (with 1 or more than 1 per fruit), or without orifice formed by curving of fruit or fruit segments (rarely); straight, or curved (slightly), or 0.5-coiled, or 1-coiled, or 1.5-coiled, or 2-coiled, or 3-coiled, or 4-coiled, or 5- to 10-coiled (rarely); not plicate, or plicate (M. plicata (P.E. Boissier) G.I. Sirjaev); not twisted, or twisted; asymmetrical, or symmetrical; circular, or falcate, or coiled; with 1 straight and 1 curved suture, or both sutures parallelly curved; widest near middle or D-shaped; not inflated; compressed, or terete, or flattened; without beak; short tapered at base; right angled with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous, or membranous, or ligneous; seed chambers externally invisible; margin not constricted, or constricted; margin constricted along both margins; margin without sulcus; margin plain, or embellished; margin with prickles, or fringe, or wing(s); wing(s) absent, or present (M. popovii (E.I. Korneva) G.I. Sirjaev); wing(s) 1; wing(s) sutural; wing(s) on 1 suture; substipitate, or nonstipitate; with all layers dehiscing, or indehiscent; splitting along suture(s). Dehiscence of valves passive. Replum invisible. Epicarp dull; monochrome; brown, or black; with surface texture uniform; glabrous, or pubescent and indurate; with hairs erect; with 1 type of pubescence, or 2 types of pubescence; tomentose (M. hypogaea E. Small); with pubescence gray, or brown; This, and perhaps 261, should be coded.; with simple hairs, or glandular hairs; pliable; with hair bases plain; glandular, or eglandular; with glandular hairs; without spines, or with spines (spines forked or more often not); smooth, or not smooth; with elevated features; veined; reticulately veined; not tuberculate, or tuberculate; with solid tubercles on each valve; tuberculate; exfoliating in part; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; dull; opaque; monochrome; without adhering pieces of testa; with hairs Check 105 to see how this should be scored; nonseptate, or subseptate, or septate; with septa thin (tissue paper-like), flexible, or thicker than paper, firm; with septa eglandular; chartaceous; not exfoliating; remaining fused to epicarp; without wings, or with wing(s) extending into epicarp (M. popovii (E.I. Korneva) G.I. Sirjaev); entire. Seed(s) 1–6(–20) (20 or more in M. scutellata (C. Linnaeus) P. Miller, Small, pers. comm., 1997); length parallel with fruit length; neither overlapping nor touching, or touching; in 1 series. Funiculus of 1 length only. Aril absent.
Seed: 1.2–7 mm long; 1–4.5 mm wide; 0.7–1.9 mm thick; not overgrown; not angular, or angular; asymmetrical; mitaform, or oblong, or rhombic, or triangular; compressed; with visible radicle and cotyledon lobes, or without 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; dull; not modified by a bloom; colored; monochrome; brown (or yellowish, reddish, or blackish), or yellow; glabrous; smooth, or not smooth; with elevated features; rugose, or wrinkled, or papillate, or transversely ridged; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; larger than punctiform; not within corona, halo, or rim. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; not concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; brown to 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; lobe tip straight; deflexed and parallel to cotyledon length; centered between cotyledons; 1/2 to nearly length of cotyledons, or equaling length of cotyledons. Plumule rudimentary; glabrous.
In an impressive number of papers over the past 20 years dealing with Medicago and related genera, Small has resolved many of the problems related to Medicago. Our species count follows Small et al. (1988), Small and Jomphe (1989a, 1989b), Small (1990a, 1990b), and Small and Brookes (1991), who included in Medicago species previously in Trigonella (21.04), and not the ca. 50 species of Heyn (1981). Small and Jomphe also illustrated seeds and fruits in line drawings, and Small et al. (1989) illustrated seeds in photographs and micrographs. Gonzáles-Andrés et al. (1999) studied the seeds of Medicago section Dendrotelis (I.T. Vassilczenko) P. Lassen. Factorovskya Eig (21.05), a monotypic and geocarpic genus recognized by Heyn, was reduced to Medicago hypogaea by Small and Brookes (1984), and is included here. Among other characters, the authors used the characteristic coiling of the fruit as evidence for the transfer to M. hypogaea. Small and Jomphe (1989b) presented a "key to the 12 sections and eight subsections of the genus" and a comprehensive illustrated key to the 83 species. The following year he circumscribed the genus based on seed characters (Small et al., 1990). Some species of Medicago are important crops throughout the temperate world. The fruits of Medicago are as diverse as they are in any faboid genus: Straight, curved, or coiled; terete, compressed or flat, and sutures spiny, tuberculate, winged, frimbiate, or plain. Most Medicago species have numerous, conspicuous veins in the fruit. These veins are located in the epicarp, unlike most other legumes which have the veins in the mesocarp.
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
