586 



TREES OF NORTH AMERICA 



Paraguay. Four species are recognized; one species extends across the Rio Grande 

 into western Texas. 



The generic name is in honor of Lewis Thdodore He'lie (1804-1867), a distinguished 

 French physician. 



1. Helietta parvifolia, Benth. 



Leaves l^'-2' long, with stout slightly club-shaped petioles, at first puberulent, 

 soon becoming glabrous, and oblong or narrowly obovate leaflets rounded or some- 

 times slightly emarginate at the apex, gradually and regularly contracted at the base, 

 entire or slightly and remotely crenulate-serrate, yellow-green and lustrous above, 

 paler below, conspicuously marked by black glandular dots, the terminal leaflet 

 '-1^' long, sometimes ' wide, and nearly twice as large as the others, persistent on 

 the branches until early spring. Flowers appearing in April and May, on slender 

 pedicels covered at first like the petioles and calyx with short dense pubescence, with 

 minute acuminate early deciduous bracts, in dichotymously branched subsessile 

 panicles on branches of the year from the axils of the upper leaves; petals white, 

 ovate, ^' long, with scattered hairs on the outer surface, and thin scabrous margins, 

 and four or five times longer than the calyx-lobes ; ovary 4-lobed, glandular-punctate 



like the slender style. Fruit ripening in October, oblong, \'-^' long, with a rigid 

 broadly ovate sometimes slightly falcate wing rounded at the apex, |' long, and con- 

 spicuously reticulate-veined. 



A slender tree, 20-25 high, with a trunk 5'-6' in diameter, rather erect branches 

 forming a small irregular head, and slender pale branchlets covered with minute 

 wart-like excrescences, faintly puberulous when they first appear, soon becoming 

 glabrous, and marked during their second year by small inconspicuous leaf -scars; or 

 a low shrub. Bark of the trunk about \' thick, covered with dark brown closely 

 appressed scales separating in large irregular patches and leaving when they fall a 

 smooth pale yellow surface. Wood hard, very heavy, close-grained, light orange 

 brown, with rather lighter colored sapwood. 



Distribution. Often forming thickets of considerable extent and abundant near 

 Rio Grande city, Texas; mesas south of the lower Rio Grande; of its largest size and 

 tree-like in habit on the limestone ridges of the Sierra Madre of Nuevo Leon. 



