Monographs Details: Thibaudia formosa (Klotzsch) Hoerold
Authority: Maguire, Bassett. 1978. The botany of the Guayana Highland--part X. Mem. New York Bot. Gard. 29: 1-288.
Description:Distribution and Ecology - Distribution. VENEZUELA. Edo. Bolivar: Gran Sabana, lower slopes of Ilu-tepui, 1000-300 m alt, 8 Feb 1952, Maguire 33250; Ilu-tepui, west-facing slopes below top escarpment, 2300-2600 m alt, 17 Mar 1952, Maguire 33466; Ilu-tepui, vicinity of Camp 3, 2100 m alt, 20 Mar 1952, Maguire 33488; Uaipantepui, west slopes, 1400 m ah, 27 Mar 1948, Phelps & Hitchcock 335; Ptari-tepui, southwest slope forest and savanna, 1500-2000 m alt, 17 Dec 1952, Maguire & Wurdack 33864, 33887; Chimanta Massif, Sarven-tepui, lower escarpment base, 1900-2050 m ah, 13 Jan 1953, Wurdack 34123; Tirtpon-tepui. rainforest on southwest side of Rio Asaporpo, 1300 m alt, 7 Jan 1953, Wurdack 34036; Chimantatepui (Torono-tepui), along base of southeast-facing sandstone bluffs from south corner northeastward, 1700 m alt, 21 May 1953, Steyermark 75500; Chimanta Massif, Central Section, along Rio Tirica above Upper Falls above Summit Camp, 1965 m alt, 7 Feb 1955, Steyermark & Wurdack 519; Churi-tepui (Muru-tepuí) talus cloud forest, northwest slopes, 2050 m alt, 30 Jan 1953, Wurdack 34267; forested summit of Sierra west of waterfall of headwaters of Rio Chicanan above high N-facing sandstone bluffs, 80 km SE of El Dorado, 700 m alt, 29 Aug 1961, Steyermark 89610; Meseta de Jaua, Cerro Sarisariiiama, cumbre, 36 mi or 60 km NE of the mission of Campamento Sanidad of the Rio Kanarakuni, 1922-2100 m alt, 22-27 Mar 1967, Steyermark 98178; Cerro Jaua, cumbre, SE portion, west of a tributary of Rio Marajano, 1810-1880 m alt, Feb-Mar 1974, Steyermark et al 109680; Km 120 south of El Dorado, 865-1050 m alt, 27-28 Dec 1970, Steyermark et al 104564; Cerro Guaiquinima, Rio Paragua, west escarpment below rim, 1500 m alt, 31 Dec 1951, Maguire 32889; Mt. Roraima, southwestern slopes, 7400 ft, 5 Jan 1939, Pinkus 128. Territorio de Amazonas: Cerro de la Nebhna, Rio Yatua, upper slope forest above Camp 4, 1500-1700 m alt, 13 Jan 1954, Maguire et al 37263; Cerro Sipapo (Paraque), lower camp savanna, 4400 ft, 15 Dec 1948, Maguire & Politi 27673; Cerro Sipapo (Paraque), North Escarpment, 23 Dec 1948, Maguire & Politi 27873; Cerro Huachamacari, Rio Cunucunuma, South Escarpment, 1400 m alt, 5 Dec 1950, Maguire et al 29852, 29866. BRAZIL. Road to Cerro de la Neblina from Río Tucano, 1250 m alt, 21 Apr 1964, Ewel 131.

Discussion:5. Thibaudia formosa (Klotzsch) Hoerold, Bot. Jahrb. 42: 274. 1909. Thibaudia roraimae Mansfeld, Notizbl. Bot. Gart. Berlin 9: 437. 1925. Both of the above taxa were based on plants collected from Mount Roraima, Venezuela. The differences as given by A. C. Smith (1932 p 411) in his key do not hold. The stamens are not actually exserted, as stated for T. roraimae, and do not protrude from the corolla in the dried specimen. The differences of "leaves nearly 3 times as long as broad" for T. formosa and "leaves less than twice as long as broad" for T. roraimae overlap in an extensive suite of specimens examined, with intergradations in the material annotated by Smith. In the following specimens determined as T. roraimae by Smith, the leaves are not "less than twice as long as broad," but vary as follows: Wurdack 34036 (slightly more than 2x); Maguire & Wurdack 33887 (2x); Steyermark & Dunsterville 92344 (slightly over 2x); Steyermark & Wurdack 519 (2x to over 2x); Wurdack 34267 (from less than 2x to 2x); Maguire & Wurdack 33864 (slightly more than 2xto 2x); Phelps & Hitchcock 335 (2x). The type photo of T. roraimae shows leaves less than twice as long as broad. Maguire 33250 has leaves slightly less than twice as long as broad, as has also the coUection of Wurdack 34123, the latter specimen closer to the leaf shape shown on the type photo. On the type photo one flower shows the stamens slightly exserted, but on another flower equaling the length of the corolla lobes. Among the material cited above, Wurdack 34123 is the only one approaching a flower with stamens nearly exserted, but actually they merely reach just short of the length of the coroUa lobes. The other flowering material determined by Smith as T. roraimae has the anthers shorter than the corolla lobe length, and not exserted as on one of the flowers shown in the type photo. However, since Smith indicates in his key (1932, p 411) that T. formosa has stamens "not exserted or barely so," there is left httle choice in deciding between "barely exserted" and "exserted" on the specimens examined. Similarly variable in the specimens identified as T.formosa are the leaves. In Smith's key the leaves are stated to be "nearly three times as long as broad," but the following specimens indicate the intergradation in this character as compared with T. roraimae; Maguire 33488 (slighfly over 2x); Maguire 32889 (slighfly over 2x); Maguire 33466 (slighfly over 2x); Pinkus 128 (2x to slighfly over 2x). In most of the specimens cited the corollas are not sufficienfly mature to show the degree of exsertion of the stamens. Since this character does not seem to have significant importance nor correlation value in the case of these two taxa, it would appear necessary to combine T. roraimae Mansf. with T.formosa Kl.
Distribution:Venezuela South America|