Monographs Details: Mimosa bathyrrhena Barneby
Authors:Rupert C. Barneby
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.
Family:Mimosaceae
Synonyms:Mimosa furfuracea Benth.
Description:Species Description - Unarmed shrubs ±2 m, the young branches, lf-axes and peduncles densely softly pilose with sordid or lutescent plumose setae to 0.7-1 mm, the dull-olivaceous foliage subconcolorous, the lfts charged on both faces with stalked stelliform setae 0.2-0.3 mm tall, the ovoid or subglobose capitula solitary or 2-3 together in axil of coevally expanding lvs, the amorphous cocoon-like pods immersed in foliage. Stipules caducous, those of primary lvs not seen, those of axillary spurs triangular-lanceolate 4-6 mm, dorsally stellate-lanate. Leaf-stalks (3-)4-7 cm, the petiole ±2-4 cm, at middle 0.55-1 mm diam., the one interpinnal segment 1-3 cm; pinnae so far as known exactly 2-jug., the distal pair longer, their rachis 5-11 cm and the longer interfoliolar segments 47 mm; lfts of distal pinnae (9-) 10-16-jug., decrescent proximally and upward subequilong, the unequal first pair 2-3.5 mm distant from subulate paraphyllidia 1-1.5 mm, the blades obliquely ovate-oblong from semicordate base, deltate-apiculate at apex, those near mid-rachis 8-16.5 x 3.5-6 mm, 2.3-2.8 times as long as wide, all veinless above, beneath 2(-3)-nerved from pulvinule, the slender, scarcely excentric midrib weakly 1-2-branched beyond middle, the inner (or only) posterior nerve expiring near or short of mid-blade, the outer posterior one very short or obsolete. Peduncles ±2-3.5 cm; capitula not seen at anthesis but calculated from fl-size ±6 mm diam. without filaments, the receptacle 4-5 mm long; bracts (few seen) linear-oblanceolate ±3-3.5 x 0.4-0.6 mm, tomentulose on both faces from middle upward, caducous; flowers 4-merous 4-androus, apparently all bisexual; calyx membranous shallow-campanulate ±0.3 mm, the undulately truncate rim minutely ciliolate; corolla turbinate 2.5 mm, the lanceolate concave lobes ±1.3 x 0.6 mm, the tube retrostrigulose with simple hairs, the tip of lobes yellowish-stellate; filaments yellow when dry, monadelphous through ±0.5 mm and alternating with staminodia free for ±0.4 mm, exserted 2.5 mm. Pods (not seen fully ripe) several per capitulum, sessile, in profile (disregarding vesture) ±1.5-3 x 0.6 cm, the shallowly constricted replum and the almost plane thin-textured valves alike concealed by a dense fleece of slender pliant plumose setae to 5 mm, these whitish at base and lutescent distally; dehiscence not seen (but probably craspedial).

Distribution and Ecology - On stream-bank near 1000 m, on sandstone substrate, known only from Sa. das Almas e. of Ponta Grossa, ±25°10'S, 50°W in e.-centr. Paraná, Brazil.—Fl. (?-)VII.

Discussion:

Mimosa bathyrrhena, despite its capitate rather than spicate inflorescence, is similar to M. furfuracea, from which it differs in corollas stellate only distally and otherwise retrostrigulose, and in the long dense wool, consisting of slender plumose setae, that cloaks the pod.

Distribution:Brazil South America| ParanĂ¡ Brazil South America|