Mimosa paraguariae Micheli
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. 1991. Sensitivae Censitae. A description of the genus Mimosa Linnaeus (Mimosaceae) in the New World. Mem. New York Bot. Gard. 65: 1-835.
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Family
Mimosaceae
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Scientific Name
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Type
146. Mimosa paraguariae M. Micheli, Mem. Soc. Phys. Geneve 28(7): 59. 1883.—Typus infra sub var. paraguariae indicatur.
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Description
Species Description - Unarmed, densely leafy, amply microphyllidious subshrubs and small shrubs (3-)4-l 2 dm with proximally defoliate slender trunks erect and ascending from slenderly fusiform woody root or xylopodium, villosulous and viscid-hispidulous throughout with fine whitish hairs and erect gland- tipped setae or setulae to 0.3-4 mm, the olivaceous foliage concolorous, the firm plane, dull or resinously sublustrous lfts thinly puberulent on both faces, glandular-setulose-ciliate, the globose capitula either all axillary and immersed in foliage or initially forming a shortly exserted but usually hysteranthously foliate pseudoraceme terminal to primary stem or lateral branchlets. Stipules either erect or recurved, sub-herbaceous ovate or lanceolate, acute or acuminate and mucronate 2-4(-4.5) x 1-2.5 mm, bluntly carinate dorsally or when broad subpinnately nerved, pubescent like stem, persistent. Leaf-stalks 2-8(- 9.5) cm, the petiole including (or rarely reduced to) pulvinus (1 —)2— 17 mm, at middle 0.5-0.9 mm diam., the interpinnal segments (3-)4-12 mm, the ventral groove continuous between pinna-pairs (spicules 0); pinnae of major lvs (3-)4- 8-jug. (of some distal lvs of some plants only 2-4-jug., not further described), decrescent proximally but distally subequilong, the axis of longer ones (1.5-)2-4.5 cm, the interfoliolar segments 0.8-2(-2.4) mm; lfts of longer pinnae 15-27-, rarely 12-14-jug., the first pair 0.3-1.3 mm distant from suborbicular, ovate, or lanceolate, obtuse or apiculate paraphyllidia 0.3-1 mm, a little decrescent at each end of rachis, the blades oblong or oblong-elliptic from oblique, shallowly cordate base, obtuse at apex, those at mid-rachis (3-)4-9(-9.5) x 1.3-2.4(-3) mm, 2.3-4.2 times as long as wide, all veinless above, beneath mostly 4-nerved from pulvinule, the centric midrib weakly 1 (-2)-branched distally or essentially simple, the one anterior and the inner posterior nerve submarginal and produced nearly to tip of lft, the outer posterior nerve weak and short. Peduncles solitary and fasciculate by 2-3, (1.2-) 1.5-9 cm; capitula without filaments 6.5-10.5 (-12) mm diam.; bracts linear-oblanceolate or spatulate 2-4.5 x 0.25-0.45 mm, glandular-setulose dorsally, only exceptionally a trifle longer than submature fl-buds, deciduous; flowers 4-merous 8-androus, most bisexual; calyx membranous campanulate 0.25-0.65 mm, the sub-truncate rim usually with a few filiform setulae or minute gland-tipped hairs, or with both, but none over 0.5 mm and sometimes all wanting; corolla narrowly funnelform (2.6-)2.8-4.7 mm, the glabrous tube early becoming pallid-membranous below the sinuses between lobes, appearing vertically striped in age, the ovate, nearly plane 1-nerved lobes 0.8-1.3 x 0.6-1 mm, usually at once thinly hispidulous and glandular-setulose but the plain hairs sometimes wanting and the setulae sometimes few and short; filaments pink, adnate at base to an obscure stemonozone 0.2-0.4 mm, exserted 5.5-11.5 mm; ovary densely glandular. Pods numerous in dense but not incompressible clusters, sessile, in profile narrowly oblong and lunately incurved ±10-19 x 3-4 mm, 3-6-seeded, the undulately constricted replum ±0.3-0.4 mm diam., together with valves at once villosulous and densely hispid with yellowish gland-tipped setae to ± 2 mm, the fully ripe valves (seldom observed) breaking up into individually dehiscent free-falling articles ±2.5-3 mm long; ripe seeds not seen.
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Discussion
Mimosa paraguariae was assigned by Micheli to ser. Leptopodae, later transferred by Hassler (1910b: 7) to ser. Asperatae where thought to be related to M. adenocarpa, and at last recognized by Burkart (1948: 61) as a member of ser. Stipellares, of which it has the enlarged paraphyllidia that resemble diminutive true leaflets. Its nearest relative in this series is M. iperoensis, which see for discussion of differences. It appears far removed from M. adenocarpa by relatively broad herbaceous stipules, absence of aculei, and lack of interpinnal spicules. The stipules vary somewhat in absolute and proportionate width, but I feel confident that the Paraguayan plants segregated by Hassler as a subspecies of Bahian M. cordistipula are nothing other than broad-stipulate individuals of M. paraguariae sens. lat., of which they have all other characters, including the characteristic pod. True M. cordistipula has much in common with M. paraguariae in the way of stipules and indumentum, but differs in spinulose-tipped leaf-stalks and leaflets, in trimerous flowers, in fruticulose habit of growth, and in conspicuously different ecology. The also Bahian M. ulbrichiana, closely akin to M. cordistipula and likewise trimerous, superficially resembles M. paraguariae in foliage and indumentum, but has essentially veinless leaflets, and pods merely glandular-puberulent, not viscidly hispid.
While M. paraguariae appears stable in characters of flower and pod it varies in leaf-formula and particularly in quality of pubescence. Singly or together these provide characters that support several varietal categories already described by Hassler, but here maintained in slightly modified form.