Bidens cordifolia Sch. Bip., Flora 39: 36. 1856.

Wagner, Warren L., Clark, John R. & Lorence, David H., 2014, Revision of endemic Marquesas Islands Bidens (Asteraceae, Coreopsideae), PhytoKeys 38, pp. 37-67 : 54-55

9. Bidens cordifolia Sch. Bip., Flora 39: 36. 1856. Figure 3C-D

Coreopsis cordifolia (Sch. Bip.) Drake, Ill. Fl. Ins. Mar. Pac.: 208. 1890.

Campylotheca cordifolia (Sch. Bip.) F. Br., Bernice P. Bishop Mus. Bull. 130: 357. 1935.

Type.

Marquesas Islands. Nuku Hiva, D.E.S.A. Jardin 199 (holotype: P).

Description.

Erect subshrubs 0.4-1 m tall; young stems and leaves moderately to densely pubescent. Leaves simple or compound and trifoliolate, 6-16 cm long including petiole, blade elliptic to elliptic-lanceolate, 4-9 × 2-4.8 cm, moderately pubescent, especially on lower surface, midrib, veins, and in a line along the petiole, margins serrate, apex acuminate to caudate. Heads usually 5, in cymes terminating main stem and lateral branches, 5-10 mm in diameter excluding rays, peduncles 1.5-4 cm long, sparsely pubescent, hair becoming denser near the heads; outer involucral bracts 5-9 mm long, oblong-elliptic, spreading, well differentiated from inner bracts, moderately to sparsely ciliate; ray florets usually 6-13 per head, sterile, rays yellow, ca. 15 × 4 mm; disk florets ca. 30, perfect. Achenes black, straight, ca. 3 × 0.5 mm, margins setose; pappus usually of 2-3 irregular antrorse barbed awns.

Distribution.

Marquesas Islands, occurring only in a relative small area of the Toovii Plateau on Nuku Hiva, from 750-1130 m.

Habitat.

Bidens cordifolia is known from montane wet shrubland or low forest with Metrosideros collina and Weinmannia marquesan a with fern understory along with other shrubs and trees such as species of Coprosma , Crossostylis , Cyrtandra , Dicranopteris , Geniostoma , and Myrsine .

Conservation status.

Proposed IUCN Red List Category Critically Endangered (CR), criteria B1ab, B2a,b (i-iii): B1, total extent of occurrence less than 100 km² (less than 10 km²); a,b, known from a single location; B2a, area of occupancy estimated to be less than 10 km²; B2b (i-iii), habitat continuing decline inferred. The suitable habitat for Bidens cordifolia on Nuku Huka (ca. 340 km²) is indicated as an endangered environment, threatened by human activity (deforestation, fire), feral animals (goats), and invasive plants, thus reducing the extent of the forest.

Specimens examined.

Marquesas Islands. Nuku Hiva: Toovii and road from Taiohae Bay to Toovii, 750 m, 3 Aug 1988, Wagner & Lorence 6258 (BISH, US); Toovii, Ooumu area, top of Tapueahu Valley off new hwy, 1067-1128 m, 8°51"S/140°19"W, 20-22 Sep 1995, Wood & Perlman 4600 (BISH, P, PAP, PTBG, US).

Discussion.

Bidens cordifolia is one of the least known species of Bidens in the Marquesas Islands. We have seen only two collections we refer to this species as well as images taken by Jean-François Butaud in 2008 and 2009 of additional populations. In addition to these collections and observations this species was only known from the type and a collection made in 1840 (Barclay 3213, BM) as cited by Sherff (1937).

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.