C. tocantina Ducke, Arch. Jard. Bot. Rio de Janeiro 3: 71. 1922. — "[BRAZIL. Para:]... prope stationem Arumateua viae ferreae alcobacensis in regione fluvii Tocantins cataractarum inferiorum, l[egit] A. Ducke 3-1-1915, n. 15.607." — Holotypus, RB n.v.; isotypus, MG = photo + clastotypus, F 602319!.

C. sessilis sensu Bentham, 1844: 103; 1875: 545; 1876: 414; Lewis, 1987: 176.

C. axillaris sensu Harley & Simmons, 1986: 114; Lewis, 1987: 171, pl. 10, fig. B.

C. tocantina sensu Ducke, 1949: 50.

Dimorphic in habit and stature, most commonly a) suffruticose, with diffuse-ascending stems ±2-5 dm dying back annually to a pallid creeping rhizome (hence forming dwarf thickets), less often (but sympatrically) b) a spindly shrub 1—2(—3) m tall, with old defoliate stems regenerating (in sheltered places, at edge of woods) through two or more seasons, the sessile or subsessile, ± hemispherical capitula borne singly or two together at top of short-shoots axillary to primary lvs of long-shoots, the short-shoots often densely thatched with bifariously imbricate stipules but sometimes reduced to as few as two nodes, the capitulum then appearing axillary to a primary lf but in reality separated from the leaf by two or more bracts; vesture variable, the stems often glabrous, sometimes puberulent or thinly hirsutulous, the lf-axes always ventrally puberulent or hirsutulous, the firm plane bicolored, ventrally lustrous lfts always glabrous on upper face and nearly so on lower face, their margin either smooth or ciliate with stiff spreading-ascending hairs to 0.2-0.7 mm. Lf-formula i/(17—)21—39; lf-spurs l-2.5(-3) mm; stipules lanceolate, narrowly ovate, or sublinear 1.5-9 x 0.7-2.2 mm, striate, commonly glabrous dorsally but occasionally hirsutulous, sometimes ciliate; lf-stks including swollen base and apex 1-7 mm, the terminal appendage 1.5-5 mm; rachis of longer pinnae (3.5-)4-8(-10) cm, the longer interfoliolar segments (1—) 1.3—2.6(—3) mm; lft-pulvinules 0.2-0.4 mm, nearly twice as wide; lfts a trifle shorter at each end of rachis, elsewhere equilong or nearly so, in outline lanceolate (narrow-ovate) from shallowly semicordate base, abruptly acuminate-mucronate, 7—13(—14) x 1.7-3 mm, (3-)3.4-4.5 times as long as wide; venation palmate-pinnate, the slightly displaced midrib giving rise on each side to ±7-11 short brochidodrome secondary nerves, the 1-2 posterior and sometimes one anterior primary nerve not attaining mid-blade, the venulation prominulous on both faces. Peduncles <2 mm, often obsolete; capitula ±9-24-fld, the fls sessile or raised on a solid pediment to 0.2 mm, almost always heteromorphic, the androecial tube of the peripheral ones included or exserted to 2.5(-3) mm, 1-4 distal ones a trifle larger but scarcely broader, their androecial tube exserted 4—9 mm; bracts striate, shorter than calyx; perianth sharply striate from base to apex, often glabrous, less often white-hirsutulous distally; PERIPHERAL FLS: calyx campanulate or turbinate-campanulate, sometimes deeply so, 1.9-3.1 x 1.2-1.8 mm, the depressed-deltate, often unequal teeth 0.15-0.5 mm; corolla (4.3-)4.5-6.8 mm, the ovate, dorsally convex lobes 1.2-2.5 x 0.8-1.6 mm; androecium (8-)10-16-merous, to 2.4—3.7 cm, the stemonozone 0.8-1.5 mm, the tube 4-7.5(-9) mm, the tassel pink or crimson; ovary glabrous; style filiform, the stigma truncate-poriform; intrastaminal nectary 0. Pod not seen.

Eastern Brazil in lat. 3°30'-18°S: best known from Chapada Diamantina in Bahia and the upper S. Francisco Basin in Minas Gerais, where found in campo cerrado and campo rupestre, mostly between 600 and 1200 m; recorded once from the Ilha de Balsas in s.-e. Maranhão, in chapadão at 300 m; once from Piauí (Sa. da Lagoa, not located, not mapped) and collected several times in the lower Tocantins Valley near Tucuruí Reservoir, on white sand campirana at 70 m. — Map 28. — Fl. (XI-)I-III(-V).

Calliandra sessilis can be recognized, in the context of sect. Androcallis, by unijugate pinnae, sessile or subsessile capitula, and oblique rootstocks which give rise to stoloniferous thickets. Flowering stems commonly arise directly from the rhizome, but sometimes persist as slender woody trunks. The relatively uncommon fruticose form has been found in Bahia (Harley 19978, NY) and in Para (Lisboa 1252, NY), in both cases close to the diffuse rhizomatous, functionally herbaceous form. No differences in leaf or in individual flower are correlated with the variations in stature, and the growth-forms seem to be no more than aspects of one variable species. There is some variation among specimens in length of the floriferous brachyblasts, C. axillaris sens. str. being the state in which one or two capitula are borne together on a very short or even obscure branchlet axillary to a coeval leaf, whereas C. sessilis sens. str. is the state in which the capitula arise from near apex of an older brachyblast thatched with closely imbricate, defoliate stipules. Harley recorded the flowers of his no. 15978 as intensely fragrant.