Mimosa calocephala Mart.

• 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

• Scientific Name

  Mimosa calocephala Mart.

• Type

  395. Mimosa calocephala Martius, Flora 21(2, Beibl. 4-5): 53 (=Herb. fl. bras. 133). 1838.-Typus infra sub var. calocephala indicatur.

• Description

  
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  Species Description - Unarmed subshrubs with erect or incurved-ascending, simple or distally few-branched stems 3-5 dm and at base 2.5-4 mm diam., proximally hispid with ascending setae to ± 1 mm and distally like back of lf-stks and peduncles silky with longer, eventually matted-woolly flagelliform setae, the dry foliage pinkish-brown subglaucescent, the firm plane, continuously comeous-marginate lfts facially glabrous (except dorsal face of first pair), setose-ciliate, the relatively stout peduncles solitary in distal lf-axils or 2-3 of the furthest ones exserted from foliage. Stipules firm erect lanceolate or lance-ovate 4-8 x 1-2 mm, densely hispid-setose dorsally, glabrous within, either persistent or tardily deciduous. Leaf-stalks of lvs at and below midstem either reduced to pulvinus or at most 12 mm, that of upper lvs always obsolete or almost so; pinnae 1 -jug., widely spreading, their rachis 5.5-10 cm, rounded dorsally, keeled ventrally and laterally, shallowly excavated between successive pulvinules, the longer interfoliolar segments 2-5 mm; lfts 1829-jug., decrescent near each end of rachis, the moderately unequal first pair close to small paraphyllidia concealed by setae, all obliquely lance-oblong, elliptic, or oblong-elliptic from shallowly semicordate base, either obtuse-mucronate or deltately subacute, the longer ones 7-15 x 2.5-4mm, 1.7-4.5 times as long as wide, the blades all veinless above, beneath 5-7-nerved from pulvinule, the almost straight midrib dividing blade 1:2.5-3, the inner posterior nerve almost attaining blade apex, the one weaker anterior nerve and other posterior nerves shorter, expiring within the margin, the forwardly subappressed cilia free for 0.5-1.3 mm. Peduncles 2-5.5 cm; capitula subglobose, dense and hard, without filaments (10—) 11-20 mm diam.; receptacle hispid; bracts 3-5 x 0.2-0.8 mm, distally setose on back and margins; flowers 4-merous 4-androus, many proximal ones staminate; calyx narrowly vaseshaped , basally attenuate, paleaceous, 3-7 mm, either glabrous or basally ciliolate, the tube 1-3.5 mm, the lobes 1.8-3.5 mm, setiform-decompound ± half-way to base; corollas subcylindric 3.8-8 mm, glabrous, the cymbiform, either subcorneous or scarcely thickened, dorsally carinate and lustrous lobes 1-1.3 x 0.4-0.55 mm; filaments (of var. calocephala, otherwise unknown) pink, monadelphous through ±2.5 mm and the tube basally adnate to corolla, exserted ±8 mm. Pods several from near and beyond mid-capitulum, sessile and embedded at base in persistent sterile fls, in profile obovate-elliptic to oblong-elliptic and (l-)2-3-seeded or oblong-oblanceolate 4-seeded, (8-) 12-18 x 5 mm, the replum 0.2-0.45 mm wide, shallowly constricted between seeds, minutely apiculate, hispid with pluriseriate setae to ±1.5-2 mm, the firmly papery valves hispidly pilose or silky-setose with tapering, minutely scaberulous setae nearly as long as or a little longer than those of replum, when ripe separating from replum and breaking up into free-falling, individually indehiscent biconvex articles 3.5-6 mm long; seeds (few seen) lentiform 3-3.5 x 2.7-3 mm, the smooth testa either light-brown or fuscous, sublustrous.

• Discussion

  Mimosa calocephala is very closely related to M. hypoglauca sensu lato, and when better known may perhaps be viewed as a series of large-flowered, therefore fat-headed forms or varieties of that species, culminating in the extremely large-flowered var. pohlii. The firm glaucescent, corneously marginate leaflets and dense consistency of the capitula at anthesis recall some unarmed forms of M. dolens, but the large paleaceous calyx, the monadelphous filaments, and the aeropetal maturation of the capitula argue against close relationship in that direction. Moreover the craspedium is that of ser. Polycephalae.