Robinsonella discolor is a small tree to 12m high, found in northeastern Mexico (states of Tamaulipas, San Luis Potosí, Hidalgo). This tree is typically found growing at elevations from 300-1100m in humid locations of deciduous tropical forest, sub-deciduous tropical forest (i.e. similar to but not strictly deciduous tropical forest), as well as in oak woods. The small white flowers occur in profusion anytime from January through April. Although not common, this species is relatively frequent in the extreme north-east of the state of Querétaro. For this reason, and its occurrence in some secondary communities, it is not considered vulnerable to extinction.
Historical Reference: Robinsonella discolor. Tree 6 to 9m. high, glabrous, with brownish gray cortex; leaves ovate, cuspidate, subacuminate, blunt at the apex, cordate or subcordate at base, sometimes unequal-sided, 4 to 5 cm. long, 2.5 to nearly 4 cm. broad, on petioles 1 to 1.5 cm. long, discolorous (covered with a line but dense tomentum), green above, canesccut below; sepals ovate; petals white, 7 mm. long; fruit borne on pedicels, often about 2 cm. long toward the extremities of short lateral branchlets and at the apex; pedicels articulated about the middle, solitary or in pairs; calyx about two-thirds the length of the carpels; sepals ovate, acute, puberulous; carpels about 12, stellately hairy, especially on the back, not quite 1 cm. long; seed dark brown, subtriangular, hairy in parts.
Collected by Mr. C. G. Pringle on limestone hills, Las Palinas, San Luis Potosi, altitude 90 meters, April 27, 1894 (No. 5767), and March 2, 1899 (No. 8007).
This species differs from R. cordata in not having villous petioles, in the color and character of the pubescence on the leaves, etc. Subscribers to Mr. Pringle's elegant sets of Mexican plants will doubtless find it in this year's distribution. Mr. Pringle states that this species is a slender tree found on the mountains of eastern San Luis Potosi, thence to Tampico.
Adding this species to those described in Garden and Forest for Juno, 1897, the genus will now consist of R. cordata, R. divergens, R. lindeniana, and R. discolor. The type of tho last named will be found in the U. S. National Herbarium, Washington.
Fragments of still another species have recently been sent to Mr. Rose from Honduras, and while there is no question as to its generic position and its distinctness from the four other species, yet it seems best to withhold it until further material has come to light. Collectors in Central America and curators of Herbaria will confer a great favor if they can communicate any material which will help us diagnose this species fully.
Contributions from the United States National Herbarium, Volume 5
Published by Smithsonian Institution Press, 1901
