Checklist of Bolivian Compositae - Royal Botanic Gardens, Kew

Key to species
1. Leaves simple 2
Leaves divided, bipinnatisect 3
2. (1) Capitula in 3–4-headed corymbs; leaf apices entire I. herzogii
Capitula solitary; leaf apices 3–7-dentate
I. acaule
3. (1) Ray limb 6–9 mm long; capitula 25–35 mm diam.; leaf segments 0.5–3 mm wide I. hoffmannii
Ray limb 18–25 mm long; capitula 30–50 mm diam.; leaf segments 0.2–0.7 mm wide
I. peucedanifolium
Isostigma acaule (Baker) Chodat, Bull. Herb. Boissier, ser. 2, 1(4): 417 (1901).
Bidens acaulis Baker in Mart., Fl. Bras. 6(3): 247 (1884). Type: ‗Habitat in Paraguay, ad Arégua locis argillosis:
Balansa n. 913!‘. [Fleurs d‘un pourpre foncé./Plaîne d‘Arégua, dans les terrains argileux. Janvier
1875.]Holotype: K (divided into two sheets post-description!); isotype: LE. Note: There are two sheets of
this collection at Kew, one separate fro mthe other after the name was published. One has the original
Balansa printed label mounted on it (with Baker‘s addition of the species name), with a large cut out
portion, the sheet subsequently remounted onto a full herbarium sheet. The other specimen was clearly
separated from this sheet (the profile of the cut edges matches exactly) and mounted onto a full herbarium
sheet. The smaller portion has had a ‗Herb. Hort. Bot. Reg. Kew‘ label added, with essentially all of the
information (except the collector‘s number) found on the ‗holotype‘; the label is also marked ‗Half sheet of
Bidens acaulis, Baker‘. Both sheets have been determined by Sherff, although he mentioned nothing about
the two sheets in his revision of the genus (Sherff, 1926). Rather oddly, Peter (2009: 23) has stated that
Sherff (1926: 246) lectotypified this name based on the Kew material; Sherff merely mentioned ‗type in
Herb. Kew; cotype, Herb. Hort. Petrop.‘.
Isostigma vailianum [as vailiana] Britton, Ann. New York Acad. Sci 7(1–5): 149 (1893). Type: [Paraguay: ]
‗Limpio, ([Morong] 734). May.‘ Holotype: NY (00180263); isotypes: BM, F (18057), GH, K, US (00049958).
Bolivia (Santa Cruz), Paraguay.
Cerrado, cerradão, grassland, swampy areas, disturbed ground.
225 m
August–May.
Santa Cruz: Wood et al. 25663 (K, USZ).
Isostigma crithmifolium Less., Linnaea 6(3): 515 (1831) = Isostigma peucedanifolium (Spreng.) Less.
*Isostigma herzogii Hassl., Repert. Spec. Nov. Regni Veg. 7: 358 (1909). Type: ‗Bolivia: Häufig im Kamp von
Santiago de Chuquitos, wie Nigritella duftend, Bl. schwartz-rot, ca. 600 m, Mai 1907. Herzog no. 617.‘
Holotype: Z (000003585); isotype: G. Note: The material in Z has been annotated by Hassler.
Bolivia (Chuquisaca, Santa Cruz, Tarija), Paraguay.
Rocky slopes, loose shaley slopes, cerrado, Chaco forest, shrubby areas, pasture, often in dry, frequently
burnt grassland [sand dunes].
400–1900 m.
February–May.
Chuquisaca: Wood 9611 (K).
Santa Cruz: Wood et al. 21807 (K).
*Isostigma hoffmannii Kuntze, Revis. Gen. Pl. 3(3): 160 (1898). Type: ‗Bolivia: 400 m Rio Yapacani.‘
[‗BOLIVIA. Rio Yapacani, 400 m, Jun 1892, Kuntze s.n.‘ – according to Wetter & Zanoni, 1985: 333] Holotype:
?NY (00180261); isotype B 2ú; US (00701982). Note: Sherff (1926: 250) merely mentioned the ‗Type
specimen‘ as being 2 sheets in B. This has been interpreted by Peter (2009: 25) as a lectotypification; Peter
went on to lectotypify the name again based on the specimen in NY. However, the sheet in NY is clearly
marked as both as lectotype (on a determinavit label by Peter) and as an isolectotype (on a verification label
by T. Zanoni).
Isostigma lorentzii Hieron. ex Sherff, Bot. Gaz. 81(3): 250 (1926), nom. nud. pro syn.
Argentina, Bolivia (Santa Cruz), Paraguay.
Cerrado, grassland (often subject to frequent fires), swampy areas, riverbanks, open forest [stabilized dunes].
0–500 m.
October – July.