Monographs Details: Thysanostemon fanshawei Maguire
Authority: Maguire, Bassett & Wurdack, John J. 1964. The botany of the Guayana Highland--Part V. Mem. New York Bot. Gard. 10: 1-278.
Family:Clusiaceae
Description:Latin Diagnosis - Arbor parva, latice flavido; ramulis tenuibus, laevibus, castaneis, internodiis evidenter 2-3 cm longis; foliis oppositis, laminis subcoriaceis vel coriaceis oblongis vel ellipticis vel oblanceolato-oblongis, vulgo 12-15 cm longis, 4.0-4.5 cm latis, costa prominenti, venis lateralibus horizontaliter parallelis prominulis, evidenter nigro-punctatis, apice abrupte acuminato, conduplicato, basi obtusa aliquantum vel valde conduplicata, petiolis 12-15 mm longis, ca. 2.5 mm crassis, aliquantis quadrangularibus, in dorso anguste alatis, transverse tessellatis; pedunculo laevi, subclavato ca. 2 cm longo; sepalis marcescentibus; floribus non visis; fructibus ovoideo-conicis, abrupte oblique acuminatis, baccatis immaturis, maturis siccantibus, pericarpiis laevibus caperatis tenue chartaceis; seminibus paucis, possibiliter 3-4, oblique ovoideis, saepe compressis, ca. 3.0-3.5 cm longis, 2.5 cm latis, testa laevi tenui indurata.

Discussion:

Fig. 61, A-E.

Type. Tree 30 feet high, 4 inch diam, from damp places in Kakaralli-Clump Wallaba forest, mile 107, Bartica-Potaro Road, British Guiana, 11 Nov 1943, D. B. Fanshawe 1446 (F.D. 4182) (holotype K, isotype Georgetown Forest Dept.).

The collector, D. B. Fanshawe, a keen observer and competent botanist, in field notes described the fruit as ''ovoid conical, slightly twisted, pale green—pericarp soft—seeds 8, oblong, rounded on one side, br., embedded in pith." In the two fruits before m e the indications are that no more than four mature seed could be fitted into the fruit shell.

There is little doubt as to the immediate relationship of Thysanostemon fanshawei with T. pakaraimae, although for the first, flowers are not available, and for the second no fruiting material has been seen. Both are represented only by the type collections. The distinguishing and differentiating features employed here are foliar, but the distinction is unmistakable.