Monographs Details: Rhytidophyllum auriculatum Hook.
Authority: Britton, Nathaniel L. Flora Borinqueña.
Description:Species Description - Restricted in natural distribution to wet or moist, rocky places in the central, western and northwestern parts of Porto Rico, and to parts of Santo Domingo and Haiti, this little-branched, large-leaved, glandular-velvety shrub is of unusual aspect and interest. A number of other kinds of plants have similar distribution, growing only on the two islands, separated by the Mona passage, which is about 130 kilometers wide; this occurrence of identical plant species has been suggested to be indicative of former land-connection between Porto Rico and Santo Domingo at some remote geological period; it may be pointed out, however, that seeds may be transported through the air by hurricane winds to much greater distances.
Rhytidophyllum (wrinkled leaf) a genus established by Martius in 1829, has about 10 species, shrubs and small trees, all natives only of West Indian islands, and the one here illustrated the only one growing in Porto Rico. Their leaves are alternate, mostly long, with short stalks. The rather large, irregular flowers are borne in long-stalked, axillary clusters; the tube of the calyx is attached to the ovary, with short lobes; the narrowly bell-shaped corolla has a curved tube and an oblique, 5-lobed limb; the 2 or 4 stamens are borne on the corolla-tube, above its base, their anthers coherent; the 1-celled ovary contains many ovules, the style is slender. The capsular fruit splits, partially, into 2 valves, releasing the small seeds.
Rhytidophyllum auriculatum (auricled, referring to the basal appendages of the leaves) is a little-branched, sometimes unbranched shrub, from 1 to 2 meters high, the stem and branches densely glandular-velvety. The leaves are obliquely, inversely lance-shaped, thin, rough, pointed, finely and bluntly toothed, unequal-sided, from 10 to 25 centimeters long, narrowed into stalks from 1 to 3 centimeters long, often with nearly orbicular basal appendages. The flower-clusters are borne on stalks about as long as the leaves, or longer, the individual flowers on stalks from 5 to 30 millimeters long; the velvety tube of the calyx is about 5 millimeters long, its lobes 2 or 3 millimeters long; the yellow or reddish corolla, brown within, is densely hairy and about 15 millimeters long. The ellipsoid capsule is about 12 millimeters long.
Rhytidophyllum auriculatum Hooker, Botanical Magazine 64: plate 3562. 1837.
Rhytidophyllum stipulare Urban; Stahl, Estudios sobre la Flora de Puerto Rico 6: 260. 1888.