Monographs Details: Henriquezia jenmanii K.Schum.
Authority: Maguire, Bassett & Wurdack, John J. 1964. The botany of the Guayana Highland--Part V. Mem. New York Bot. Gard. 10: 1-278.
Family:Rubiaceae
Description:Distribution and Ecology - Distribution. British Guiana, along the Mazaruni river and at its junction with the Essequibo River.BRITISH GUIANA. Mazaruni River; tree from 10 to 40 or more feet high; Sep 1880, G. S. Jenman 629 (holotype K, photo NY); Bartico Point, Essequibo and Mazaruni River junction; foreshore on sandy silt at or below tide level; 13 Sep 1942, Forest Dept. Field No. F 847 (Record No. 3583) (F, NY).

Discussion:

Reported by N. E. Brown (Trans. Linn. Soc. II 6: 33. pl. 4. 1901) on collection of Mc Connell & Quelch 711 from Mazaruni River, British Guiana ("This hand-some tree appears only to have been collected in this single locality"). Plate 33 shows the five corolla-lobes pubescent within. O n a single large detached leafblade, the apex is drawn as broadly rounded and mucronulate, while the whorls of leaf-blades at and just below the inflorescence are shown as definitely acute or acuminate.

Henriquezia jenmani is known thus far only from British Guiana and represents an isolated eastern outlier of a genus whose distribution otherwise is confined to the drainage of the Upper Rio Negro, Guainia, and Upper Orinoco of southwestern Venezuela, adjacent Colombia, and state of Amazonas in northwestern Brazil. This species is unique in the genus in having 1) all the corolla lobes, instead of one of them only, with pubescence on the inner surface, 2) glaucous lower surface of the leaf-blade with a minute dense papillate surface, and 3) a loose, ascending hirtellous pubescence on the inner surface of the stipules as contrasted with the minutely tomentose or sericeous-velutinous short tomentum of the other species.

In the original description the leaves are stated to be ternate. The herbarium specimens of Forest Dept. F 847 show leaves varying from ternate to quaternate. Although the length of the stipules is given as 1.7-2 cm long in the original description, the specimens of Forest Dept. F 847 have stipules only 0.9-1 cm long. The petioles in the original description are stated to be 2-2.5 cm long, whereas measurements of Forest Dept. F 847 specimens show petioles varying from 1-1.7 cm long; moreover, the photograph of the holotype shows petioles not exceeding 1.7 cm in length. Probably the most serious divergence is in Schumann's description of the lower surface of the leaf-blades as '' subtus opacis tomento minutissimo canescentibus reticulatis" (loc. cit. p. 135). Actually, the specimens examined of Forest Dept. F 847 have the lower surface of the leaf-blades gray-white or "glaucous," but they are glabrous and without any tomentum; instead, their surface has a dense white papillate covering over a reticulate venation. It is not glaucous, since it has no "bloom" which can be rubbed off. It is believed that Schumann's description must be re-interpreted to mean a densely gray-white papillate surface produced over a reticulate venation.

Furthermore, in the original description the corolla is stated to be 50 mm long, whereas present measurements of the Forest Dept. F 847 specimens show the corolla length as 35-41 mm. However, it has been found that corolla measurements in the other species of Henriquezia are subject to considerable variation, depending on conditions of pressure and shrinkage after drying.

The lateral branches of the inflorescence shown in the photograph of the holotype specimen at N Y attain 5 cm in length, whereas on the Forest Dept. F 847 specimens they are only 1.5-2.5 cm long. Despite the above discrepancies, however, there appears to be no doubt of the conspecific identity of the Forest Dept. F 847 specimens with the holotype of Jenman 629.

Distribution:Guyana South America|