Hevea rigidifolia (Spruce ex Bentham) Mueller- 
Argoviensis in Linnaea 84 (1865) 203; in DC. Prodr. 
15, pt. 2 (1866) 718; in Martius FI. Brasil. 11, pt. 2 
(1874) 8300—Hemsley in Hooker’s Icon. Pl. 26 (1898) 
t. 2578, figs. 11, 12, 18—Pax in Engler Pflanzenr. IV, 
147 (Heft 42) (1910) 124—Ducke in Arch. Instit. Biol. 
Veg. Rio Janeiro 2, no. 2 (1985) 235; in Bol. Téen. 
Instit. Agron. Norte no. 10 (1946) 18. 
Siphonia rigidifolia Spruce ex Bentham in Hooker's 
Journ. Bot. 6 (1854) 871. 
ORIGINAL DESCRIPTION: 
**S. rigidifolia, Spruce, MS. ; foliolis ellipticis crasso-coriaceis glabris, 
paniculis pulveraceo-tomentosis, calycibus subacuminatis, antheris 5—8 
ad basin columnae irregulariter subverticillatis.— Ramuli glabrati. 
Foliola breviter petiolulata, 5 poll. longa, 24 poll. lata, acute acumi- 
nata, margine recurva, basi cuneata, multo crassiora et rigidiora quam 
in caeteris speciebus, subtus punctis crebis albicantia. Paniculae py- 
ramidatae, semipedales. Flores pallide flavi, masculi 2 lin., foeminei 3 
lin. longi. Antherae S. luteae. Stylus evidentior. 
**A milky tree of 30 feet in height, from the caatingas of the Rio 
Uaupés R. Spruce.’’ 
EXTENDED DESCRIPTION : 
Arbor parva usque ad triginta ped. alta, 8.5 ad 10 poll. 
in diametro, latice albo. Petiolt robusti, 8-24 cm. (max- 
ima pro parte 13-17 cm.) longi, 1-8 mm. in diametro, 
teretes, cortice glabro rubicundulo-brunneo vel stram- 
ineo-brunneo, tenuiter striati, basi leviter subcarnoso- 
dilatati, apice valide biglandulosi. Petioluli robustiores, 
3-13 mm. (maxima pro parte 5-7 mm.) longi. Foliola 
valde reclinata, statu adulto valdissime coriacea (et multo 
rigidiora quam illa in genere vulgo visa), perfecte oblon- 
gato-elliptica vel saepe elongato-elliptica, basi cuneata vel 
saepe valde rotundata, apice acute cuspidato-acuminata, 
margine conspicue recurvata, 6-19.5 cm. (maxima _ pro 
parte 10-18 cm.) longa, 8.5-8.5 em. (maxima pro parte 
4.5-6.5 em.) lata, supra laevigata, pallide cinereo-viridia, 
[101 J 
