Subfamily: Faboideae.
Phylogenetic Number: 3.9.07.
Tribe: Indigofereae.
Species Studied - Species in Genus: 87 studied; ca. 730 in genus.
Fruit: A legume, or a loment (or a loment segment) (but not a true loment, see Notes); unilocular; 0.2–7.5 cm long; 0.2–0.5 cm wide; 0.2–0.6 cm thick; length less than twice as long as width, or 2–9 times longer than wide, or more than 9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx; more frequently without orifice formed by curving of fruit or fruit segments, or with orifice formed by curving of fruit or fruit segments (occasionally); straight to curved to 1-coiled; not plicate; not twisted; asymmetrical, or symmetrical; circular, or linear, or moniliform, or falcate; with 1 straight and 1 curved suture, or both sutures parallelly curved, or both sutures nearly straight; widest near middle or D-shaped; not inflated; flattened, or subtriangular, or terete, or quadrangular; without beak; long tapered at apex to short tapered at apex; aligned with longitudinal axis of fruit to oblique with longitudinal axis of fruit; long tapered at base to short tapered at base; aligned with longitudinal axis of fruit to oblique with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible; seed chambers with the raised seed chambers not torulose; margin constricted, or not constricted; margin constricted along both margins; margin without sulcus; margin plain, or embellished; margin with prickles, or wing(s); wing(s) present (in I. trifoliata C. Linnaeus fruit slightly winged along sutures and in I. glandulosa J.C. Wendland wings broader and fringed), or absent; wing(s) 4; wing(s) 0.1–0.2 mm wide; wing(s) valvular; wing(s) on both valves; nonstipitate; with all layers dehiscing, or indehiscent; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; passive. Replum invisible. Epicarp dull; monochrome (some densely minutely pubescent giving epicarp a silver appearance or silvery patches on a dark color); reddish brown, or red (brownish); with surface texture uniform; glabrous, or pubescent and indurate; with hairs erect; with 1 type of pubescence; puberulent; with pubescence gray; with pubescence uniformly distributed; with simple hairs, or glandular hairs (I. colutea (N.L. Burman) E.D. Merrill), or complex hairs; with T-shaped hairs (biramous); stiff; with hair bases plain; glandular, or eglandular; with glandular hairs, or dots, or disks (in Trifoliata group); with spines (curved), or without spines; not smooth; with elevated features; veined; longitudinally veined relative to fruit length; not tuberculate; exfoliating in part, or not exfoliating; with cracks, or without cracks; cracking transverse to fruit length; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; coriaceous. Endocarp present; visible; dull; opaque; mottled, or streaked, or bichrome; brown, or tan; with mottling more or less uniform (dark); with black overlay, or brown overlay, or red overlay (to dark reddish black); smooth; without adhering pieces of testa; septate to subseptate to nonseptate; with septa thin (tissue paper-like), flexible to thicker than paper, firm; with septa glandular, or eglandular; coriaceous, or chartaceous; not exfoliating, or exfoliating in part; remaining fused to mesocarp and epicarp; with wing(s) extending into epicarp (in I. trifoliata C. Linnaeus fruit are slightly winged along sutures and in I. glandulosa J.C. Wendland wings are broader and fringed), or without wings; entire. Seed(s) 1–18; length parallel with fruit length, or transverse to fruit length (I. luzonensis I de Kort & G Thijsse and I. zollingeriana F.A.W. Miquel); touching, or neither overlapping nor touching; in 1 series. Funiculus 0.5–1 mm long; of 1 length only; thick; straight. Aril absent.
Seed: 1–6 mm long; 0.9–3.5 mm wide; 0.6–3.5 mm thick; not overgrown; angular to not angular; symmetrical (except hilum), or asymmetrical; circular, or irregular, or linear, or quadrangular, or rectangular; terete, or quadrangular, or compressed; with surface grooved; transverse; with visible radicle and cotyledon lobes, or without visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; without hilar sinus; 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 to dull; not modified by a bloom; colored; monochrome, or mottled; with frequent mottles, or infrequent mottles; brown, or orange, or red (brownish), or tan, or yellow; with black overlay, or red overlay; glabrous; not smooth; with elevated features, or recessed features; reticulate (I. australis C.L. von Willdenow with interesting reticulation), or shagreen, or tuberculate, or tessoroid; pitted with small separate pits, or pitted with large concatenated pits (with large single pits); coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Raphe visible, or not visible; from hilum to lens; darker than testa; black; recessed. Hilum present; visible, or fully concealed; concealed by funicular remnant; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; larger than punctiform; to 5 mm long; with curved outline; elliptic; apical at apex of radicle tip (I. linifolia (C. Linnaeus) A.J. Retzius), or marginal according to radicle tip, or between cotyledon and radicle lobe; recessed; not within corona, halo, or rim. Lens discernible, or not discernible; with margins straight, or curved; irregular, or wedge-shaped; irregular, or hourglass or dumbbell-shaped; not in groove of raphe; adjacent to hilum; less than 1 mm from hilum; mounded; dissimilar color from testa; darker than testa; brownish black, or brown, or red (brownish); 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; margin entire 180 degrees from base of radicle; differing at apex (1 concealed by overarching radicle and other auriculate and concealing radicle), or similar at apex; partially concealing radicle, or not concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; white, or yellow; inner face flat; glabrous on inner face. Embryonic axis deflexed; perpendicular to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; deflexed and parallel to cotyledon length, or deflexed and parallel to cotyledon width; centered between cotyledons, or not centered between cotyledons (radicle outside 1 cotyledon and inside other, therefore junctions for each cotyledon different); less than 1/2 length of cotyledons to 1/2 to nearly length of cotyledons. Plumule rudimentary to moderately developed to well developed; glabrous.
Gillett (1958) monographed Indigofera (including Microcharis (9.04)) in tropical Africa and recognized five subgenera. Kort and Thijsse (1984) noted that Polhill (1981f) treated Indigofera with its two satellite genera Cyamopsis (9.06) and Rhynchotropis (9.03) together with the rather anomalous Madagascan genus Phylloxylon (9.01) (hitherto of unknown affinity) in tribe Indigofereae. Schrire (1995) performed extensive cladistic analyses with the Indigofereae genera and Indigofera infrageneric taxa. He concluded that I. subgen. Indigastrum (H.F. Jaubert & É. Spach) J.B. Gillett, I. subgen. Microcharis (G. Bentham) J.B. Gillett, Cyamopsis, and Rhynchotropsis formed a sister clade to the remainder of Indigofera, so he reinstated the aforementioned Indigofera subgenera as genera, Indigastrum H.F. Jaubert & É. Spach (9.05) and Microcharis. Pending a general expression of opinion by the botanical community concerning Shrire's changes, we have chosen to present Indigofera with its traditional circumscription (Gillett, 1958, 1971; Polhill 1981f). Choi and Kim (1997) equenced the ITS region of six Indigofera species, and concluded that the ITS sequence will be useful for understanding Indigofera classification and evolution. We had for study only seeds of three species of I. subgen. Indigastrum, Indigofera argyraea C.F. Ecklon & C.L.P. Zeyher (Indigastrum argyraeum (C.F. Ecklon & C.L.P. Zeyher) B.D. Schrire), Indigofera fastigiata E.H.F. Meyer (Indigastrum fastigiatum (E.H.F. Meyer) B.D. Schrire), and Indigofera parvifolia B. Heyne ex R. Wright & G.A.W. Arnott (Indigastrum parvifolium (B. Heyne ex R. Wright & G.A.W. Arnott) B.D. Schrire), and of one species of I. subgen. Microcharis, Indigofera disjuncta J.B. Gillett (Microcharis disjunta (J.B. Gillett) B.D. Schrire). The seed characteristics of these four species were congruent with those of the other 83 Indigofera species studied. The dark spots on the outer endocarp surface are "groups of swollen coloured cells rich in tannin" (Gillett, 1958, p.2), and they can form pits in the seeds. The fruits of species such as I. cryptantha G. Bentham ex W.H. Harvey, and D.A.P. Watt & Brandwijk appear to be loments, but this is not true. These fruits are dehiscent legumes and not loments separating into articles.
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
