Exostema ellipticum Griseb.

• Title

  Exostema ellipticum Griseb.

• Authors

  Nathaniel Lord Britton, Frances W. Horne

• Scientific Name

  Exostema ellipticum Griseb.

• Description

  Flora Borinqueña Exostema ellipticum Mountain Prince-wood Family Rubiaceae Madder Family Exostema ellipticum Grisebach, Memoirs of the American Academy of Arts and Sciences II. 8: 504. 1862. This shrub, or small tree, otherwise known only as inhabiting Cuba, was detected on the top of the mountainridge above Villalba, Porto Rico, by Professor Cowles, of the College of Agriculture and Mechanic Arts, in the Spring of 1925; he collected a flowering branch at this time, shown in the illustration herewith published. The plant must be rare in Porto Rico, because it has been found at no other locality; we have explored the mountains above Villalba on several occasions, but failed to see it. In Cuba it inhabits the mountains of Santa Clara and Oriente Provinces, and also the Isle of Pines. August Heinrich Rudolf Grisebach, who first described this species botanically, was an eminent German botanist, Professor in the University of Goettingen, who made very important contributions to the literature of West Indian Botany, his "Flora of the British West Indian Islands" published in four parts from 1859 to 1864, and his cataloguing and descriptions of Cuban plants being classical works of reference, now rare. For an account of the genus Exostema we refer to our description of Exostema caribaeum. Exostema ellipticum (elliptic-leaved) is a shrub, or a small tree, with smooth foliage. Its leaves are elliptic or oval, pointed or blunt, from 4.5 to 8.5 centimeters long, their rather short stalks from 4 to 10 millimeters long, the midvein rather prominent, the lateral veins obscure. The flowers are few together in loose, stalked clusters, differing from those of Exostema caribaeum of the dry, southern districts, which are solitary in the leaf-axils; their stalks vary from 4 to 20 millimeters long; the calyx is about 6 millimeters long, with short, triangular teeth; the corolla is at first white, changing to rose, its tube from 2.3 to 3 centimeters long, the narrow lobes about as long. The capsule (of specimens from Cuba) is nearly cylindric, from 1.5 to 3 centimeters long. The fruit of the Porto Rico plant is as yet unknown; the flowering specimen seems to be specifically the same as the Cuban type; it is possible, when fruit from Porto Rico is obtained, the classification may require modification.