Bidens beckiana (F. Br.) Sherff, Publ. Field Mus. Nat. Hist., Bot. Ser. 16: 80. 1937.

Wagner, Warren L., Clark, John R. & Lorence, David H., 2014, Revision of endemic Marquesas Islands Bidens (Asteraceae, Coreopsideae), PhytoKeys 38, pp. 37-67 : 55-56

10. Bidens beckiana (F. Br.) Sherff, Publ. Field Mus. Nat. Hist., Bot. Ser. 16: 80. 1937. Figure 3A-B

Campylotheca beckiana F. Br., Bernice P. Bishop Mus. Bull. 130: 359, fig. 66. 1935.

Type.

Marquesas Islands. Eiao, 20 September 1922, R.H. Beck 1529 (holotype: BISH-723228!; isotype: BISH).

Description.

Erect subshrubs 0.7-1.3 m tall. Leaves simple, 1.5-9.5 cm long including petiole, blades narrowly ovate or lanceolate, 1-7 × 0.8-4 cm, glabrous or pubescent toward the base and in a line along the petiole, margins serrulate, apex acuminate. Heads (1-)3(-4), in diffuse cymes terminating main stem and lateral branches, 5-15 mm in diameter excluding rays, peduncles 1.5-11.8 cm long, glabrous; outer involucral bracts 4-9 mm long, broad and tapering somewhat at the base, apex sometimes erose, inner bracts sometimes erose at apex; ray florets 5-11, sterile, rays yellow, 9-15 × 2-3 mm wide, apex entire or divided into 2-3 acute to rounded lobes; disk florets ca. 30-34, perfect, corollas yellow. Achenes gray, straight or slightly curved, 8-10 × 1 mm, conspicuously setose; pappus of 2 antrorse barbed awns.

Distribution.

Marquesas Islands, occurring on Eiao and Hatutaa, 150-500 m.

Habitat.

Bidens beckiana is scattered to locally common on steep slopes and ridges, ravines, or cliffs, from mesic to xeric shrublands and grasslands with Dinebra xerophila , Waltheria indica L., Cordia lutea Lam., Dodonaea viscosa , and Thespesia populnea (L.) Sol. ex Corrêa. Judging from the number of collections Bidens beckiana appears to be more common on Hatutaa than Eiao, which has populations of feral sheep, pigs, cats, and rats.

Conservation status.

Endangered (EN), criteria B2b (i-iii): B2, total area of occupancy less than 500 km² (ca. 47 km²); b (i-iii), habitat quality continuing decline inferred. The suitable habitat for Bidens beckiana on Eiao (40 km²) and Hatutaa (7 km²) is indicated as an endangered environment, threatened by feral animals, and invasive plants, thus reducing the extent of the suitable habitat.

Specimens examined.

Marquesas Islands. Eiao: North side of large valley which is south of Vaituha Valley, Opituha Valley, 320 m, 7 Jul 1988, Perlman & Florence 10051 (BISH, E, F, K, LE, MO, P, PAP, PTBG, OS, UBC, US); NW side of island, Vaituha Bay and summit ridge of island, 400 m, 1 Aug 1977, Gagné 1294 (BISH, US); Tohuanui, secteur est, 480 m, 8°0"S/140°41"W, 8 Jul 1988, Florence & Teikiteetini 9368 (BISH, CHR, K, P, PAP, PTBG, US); Tetuaenui, falaise de la crete, 500 m, 5 Aug 1987, Thibault 1083 (PAP). Hatutaa: Plateau, secteur centrale, 320 m, 7°55"S/140°34"W, 11 Jul 1988, Florence & Teikiteetini 9419 (BISH, P, PAP, US), 9426 (BISH, P, PAP, US); Plateau centrale, 150-200 m, 19 Aug 1975, Thibault 148 (BISH, US); Plateau, secteur Ouest, 280 m, 7°56"S/140°35"W, 10 Jul 1988, Florence & Perlman 9408 (BISH, CHR, P, PAP, PTBG, US); Plateau, secteur Ouest, 280 m, 7°56"S/140°35"W, 11 Jul 1988, Florence & Teikiteetini 9410 (BISH, OS, P, PAP, PTBG, US); Main ridge, top, 400 m, 23 Mar 1960, Decker 349 (BISH, US); On top, summit plateau, 320 m, 10 Jul 1988, Perlman 10064 (BISH, F, HAW, MO, P, PAP, PTBG, UBC, US); Plateau, secteur E, 320 m, 7°55"S/140°34"W, 11 Jul 1988, Florence & Teikiteetini 9427 (BISH, CHR, P, PAP, PTBG, US); Tres commun au-dessus de 200 m, 200 m, 9 Aug 1987, Thibault 1102 (PAP).

Discussion.

Bidens beckiana is characterized by having outer and inner involucral bracts that are scarcely differentiated from the pales, and very broad outer bracts that are usually somewhat constricted at the base.

Figures

Figure 3. Bidens beckiana (F. Br.) Sherff (A-B). A Distal part of plant B Head post-flowering showing involucral bracts and apex of achenes. Drawn from Florence 9368 (US) [A] and Perlman 10064 (US) [B]. Bidens cordifolia Sch. Bip. (C-D). C Distal part of plant D Head post-flowering showing involucral bracts. Drawn from Wood & Perlman 4600 (US). Bidens polycephala Sch. Bip. (E-F). E Distal part of plant F Head post-flowering showing involucral bracts and apex of achenes. Drawn from Perlman 15878 (US). Image from field shots used to augment illustration of Wood 10504.