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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [Vol. 8, No. 2 



TYPE : succulent herb, leaves dark green above, whitish-green below; flowers 

 white, fertile anthers pinkish-tinged; fruit green, seeds black; locally abundant 

 in semi-swampy pockets and on humus-covered boulders in montane forest at In- 

 termediate Camp, 900 m. altitude, Cerro Huachamacari, Territorio Amazonas, 

 Venezuela, December 4, 1950, Maguire, Cowan & Wurdack 29829; New York Bo- 

 tanical Garden. Paratypes: Cerro Huachamacari, 800 m. altitude, between Lower 

 and Upper Escarpment, November 29, 1950, Maguire, Cowan & Wurdack 29796; 

 Cerro Marahuaca, Territorio Amazonas, Venezuela, 4000' (1300 m.) altitude, May 

 11, 1949, Maguire & Maguire 29188. 



The material of this new genus was first collected by Maguire in 1949 on the 

 Kunhardt Expedition to Cerro Marahuaca. This is another of the numerous sand- 

 stone tabletop mountains in the southwestern state of Amazonas; it lies parallel 

 to the well-known Cerro Duida and only a few miles northeast of it. The south- 

 easternmost extension of Marahuaca is designated on the map (South America 

 1 : 1,000, 000-Rio Branco Sheet) as Marahuacita; it was on one of the lateral 

 ridges on the north side of the latter near the headwaters of the Rio Podamo 

 that the first material was collected. Since the one collection of it was (una- 

 voidably) a unicate, it was with the greatest satisfaction that we found the plant 

 again on the nearby mountain, Cerro Huachamacari, during the New York Bo- 

 tanical Garden's 1950-51 Expedition. As a result it was possible to collect 

 abundant material and observe it extensively in living condition. 



Altitudinally it extends from about 2500 to 4000 feet on the upper talus slopes 

 in the diffuse light of dense montane forest. It is always found growing under 

 high-moisture conditions in pockets of wet humus or in moss-covered humus ac- 

 cumulations over logs, boulders, and the like. The plants are quite uniform in all 

 respects, although a single individual was observed with a diminutive basal 

 lobe on one of the lateral leaflets. It is most frequently associated with ferns, 

 aroids, and bromeliads and is exceedingly abundant locally; above our Inter- 

 mediate Camp at 3500 feet, although the conditions were apparently identical with 

 those at slightly lower elevations, it disappeared entirely. 



The generic name refers to the acaulescent habit of the plant while the spe- 

 cific epithet is derived from the fleshy condition of the vegetative parts. 



The characters of the plant clearly ally it with the subtribe Cuspariinae of the 

 tribe Cusparieae, a group restricted to tropical America and best-represented in 

 northern South America. To this subtribe are now assigned sixteen genera and 

 twelve of these include plants with zygomorphic flowers. The zygomorphy may be 

 expres*ed in either the calyx, the corolla, the androecium, or in all these struc- 

 tures. Studies of a preliminary nature have revealed that the zygomorphic- 

 flowered genera are, for the most part, rather closely related. However, there ap- 

 pear to be at least two divergent phylogenetic lines; in one the fertile anthers 

 have developed flabellate or saccate appendages at their bases whereas the other 

 is characterized by the absence of such structures. Apocaulon is thus properly 

 assigned to the appendaged-anther group which includes Raveniopsis, Lubaria, 

 Erythrochiton, Raputia, and Galipea. It is readily separable from its near rela- 

 tive by its fleshy, acaulescent habit; by its fertile anthers cohering face to face; 

 by its long uncinate staminbdia; and by its basally alate style. The only other 

 near-herbaceous genus in the subtribe is Monnieria, one of the unappendaged- 

 anther group, from which Apocaulon is distinct by (in addition to the anther ap- 

 pendages) its more- distinctly bilabiate and curved corolla; by its relatively longer 

 and often uncinate staminodia; by its five-lobed stigma; and by its basally alate 

 style. 



