Calliandra conferta

Title

Calliandra conferta

Authors

Rupert C. Barneby

Scientific Name

Calliandra conferta Benth.

Description

49. Calliandra conferta Bentham in A. Gray, Pl. Wright. 1: 63. 1852. — "[C. Wright] 166, 167...Hills at the head of the San Felipe, in flower; and on Zacate Creek, July, in fruit; also on the Rio Grande, Texas." — Syntypi (Isely, 1972: 276), Wright 166 and 167, NY!; isosyntypi, K! = K. Neg. 15518. — Feuilleea texana O. Kuntze, Revis. Gen. Pl. 1: 187. 1891 (non F. conferta (Bentham) O. Kuntze). — Mistakenly equated with Anneslia eriophylla by Britton and Rose (1928: 59). Fig. 8

C. conferta sensu A. Gray, Pl. Wright. 2: 53.1853; Bentham, 1875: 546; Turner, 1959: 32, map 4; Isely, 1972: 275; 1973: 78, map 18; Correll & Johnston, 1979: 770.

Intricately branched, mounded or straggling, microphyll shrubs 1-3 dm, the stiffly flexuous branches brown or blanched in age, the new branchlets gray-puberulent or -pilosulous, glabrescent, the lf-axes, peduncles and dorsal face of the imbricate lfts thinly strigulose or ascending-pilosulous with fine lustrous hairs to 0.2-0.7 mm, the small firm lfts glabrous on upper face, the few-fld capitula solitary or less often geminate in axils of contemporary lvs; phyllotaxy distichous. Stipules firm, linear-lanceolate or narrowly triangular 1-2.5 x 0.2-0.5 mm, l-6(-8)-nerved dorsally, tardily deciduous by weathering. Lf-formula i/812; lf-stks 0.6-2.8 mm, at middle 0.25-0.5 mm diam, shallowly grooved ventrally; rachis of longer pinnae (5-)6-12.5 mm, the longer interfoliolar segments 0.45-1.2 mm; lft-pulvinules 0.1-0.2 mm diam, not wrinkled; lfts often decrescent near top of rachis, otherwise subequilong, the blades linear, linear- lanceolate or ovate-elliptic from shallowly auriculate base, deltately acute or apiculate, those near mid- rachis (2.3-)3-5.5 x 0.8-1.4 mm, (2.6-)3.4-4.6 times as long as wide; venation variable in strength, usually immersed on upper face and obtusely prominulous dorsally, the straight midrib displaced to divide blade 1:2-3, either simple or faintly 1-2-branched, the inner posterior primary nerve produced to or commonly beyond mid-blade. Peduncles 2.5-20 mm, usually ebracteate; capitula 2-8-fld, the receptacle not over 1 mm; bracts ovate or subulate 0.45-1 mm; pedicels 0 or obscure, not over 0.2 mm; perianth 5-merous, loosely pilosulous overall to glabrous except at apex; calyx campanulate, obtusely 5-nerved, 1-1.8 x 1.1-1.8 mm, the deltate-ovate teeth 0.35-0.6 mm; corolla narrowly campanulate (3.5-)3.8-5.2 mm, the tube 5- or weakly 10-15-nerved, the lobes 0.9-1.7 mm; androecium 20-28(-30)-merous, 7.5-14 mm, the tube 1.8-2.1 mm, the stemonozone 0.6-1.1 mm, the tassel pale pink or whitish; ovary glabrous at anthesis, silky-strigulose following fertilization; intrastaminal nectary 0. Pods erect, in profile (2-)2.6—4 x  0.4—0.6 cm, the sutural ribs in dorsal view 0.9-1.2 mm wide, the stiffly papery, when ripe stramineous valves densely white-silky-strigulose, low-convex over (1-) 2-5(-6) seeds, the ribs similarly strigulose or glabrescent; seeds plumply ovoid-discoid ±4-4.3 x 3-3.6 mm, the testa pale brown or putty-colored flecked with darker brown, the small pleurogram delicately incised.

Bare stony hilltops and thinly vegetated slopes or rocky flats, mostly on caliche soils, 30-1200 m, locally plentiful, scattered over s.-centr. and s.-w. Texas (Trans-Pecos, Edwards Plateau and South Texas Plains n.-ward to Travis County), crossing the Rio Grande very locally into n. Coahuila (Sa. de Jardín), Mexico. — Map 26. — Fl. IV-VI, sporadically later, following rains.

Calliandra conferta closely resembles C. eriophylla in most resepcts, and is easily mistaken for drought- stressed aspects of C. eriophylla which have lost the primary leaves and retain only the simpler brachyblast leaves, many or most of which may consist of only one pair of pinnae. Even these, however, have a longer primary axis. Further differential characters of C. conferta are the shorter androecium (7.5-14, not 16-27 mm long), paler pink or whitish filaments and on the average shorter, thinner-textured pods with narrower sutural ribs. An intrastaminal nectary is found at the base of almost every flower of C. eriophylla, but has not been seen in any flower of C. conferta. These relatively weak differences, in context of an almost perfectly vicariant dispersal, would seem to justify the reduction of C. conferta to varietal status, as evidently contemplated (in annotation of specimens, NY) by Isely. The complete subordination of C. conferta, in North American Flora, is, on the other hand, clearly mistaken.