RUT ACE jE. 



SILVA OF NORTH AMERICA. 



81 



HELIETTA PARVIFOLIA. 



Baretta. 



Sepals and petals 4 ; disk 4-lobed. 



Helietta parvifolia, Bentham, Hook. Icon. xiv. 66. — V. Ptelea parvifolia, Hemsley (ex. char. A. Gray in Eerh. 

 Havard, Proc. U. S. Nat. Mus. viii. No. 29, 475. — Sar- Kew.), Sot. Biol. Am. Cent. i. 170. 



gent, Garden and Forest, ii. 352. 



A slender tree, twenty or twenty-five feet in height, with a trunk five or six inches in diameter, 

 and rather erect branches forming a small irregular head ; or a low shrub. The bark of the trunk 

 is an eighth of an inch thick, the surface covered with dark brown closely appressed scales which sepa- 

 rate in large irregular patches, leaving when they fall a smooth pale yellow surface. The bark of the 

 branchlets is pale, covered with minute wart^Hhe excrescences j it is minutely puberulous when they first 

 appear, soon becoming glabrous, and is marked during the second year with small inconspicuous leaf- 

 sears. The leaves remain on the branches until March or April, when the new growth begins. They 

 are borne on stout slightly club-shaped petioleSj which are at first puberulent, and become glabrous at 

 maturity. The leaflets are oblong or narrowly obovate, rounded or sometimes slightly emarginate at 

 the apex, and gradually and regularly contracted at the base ; they are entire or slightly and remotely 

 crenulate-serrate, yellow-green and lustrous on the upper surface, paler below, and conspicuously marked 

 with black glandular dots ; the terminal leaflet, which is sometimes wanting, is half an inch to an inch 

 and a half long, sometimes half an inch broad, and nearly double the size of the two lateral leaflets. 

 The flowers, which open in April and May, are produced in dichotomously-h ranched subsessile panicles 

 on the shoots of the season from the axils of the upper leaves above which they hardly appear. The 

 flower-buds are round, obtusely-flattened, and covered with pubescence. The bracts of the pedicels are 

 minute, acuminate, and early-deciduous, and, hke the petioles and calyx, are covered at first with short 

 dense pubescence. The petals are white, ovate, an eighth of an inch long or nearly so, with scattered 

 hairs on the outer surface, and thin scabrous margins, and are four or five times longer than the calyx- 

 lobes. The disk is four-lobed with entire margins, and, like the four-lobed ovary and slender style, is 

 minutely glandular-punctate. The fruit, of which only two or three specimens appear to mature from a 

 panicle, ripens in October ; it is oblong, a quarter to a thu-d of an inch long, and produced into a rigid 

 broadly ovate, sometimes slightly falcate wing, rounded at the apex, half an inch long, and conspicu- 

 ously reticulate-veined. 



Helietta j)arvifoUa forms thickets of considerable extent near Eio Grande City in Texas, where it 

 is a common shrub. It was first noticed there by Dr. Valery Havard ^ in 1883, and is not known else- 

 where within the limits of the United States. HeHetta is rather common on the mesas south of the 

 lower Rio Grande, where it is found with the Acacias, Buckthorns, Yuccas and Cacti, the Texas Per- 

 srnimon, and the Parkinsonias, which form the characteristic features of the flora of that region, and 



^ Yal^ry Havard was born near Compifigiie in France in 1846, 

 and was edncated at Beauvois, where he followed assiduously in 

 the Agrienltural Institute courses in botany and in other depart- 

 ments of Natural History. Havard emigrated in 18GG to the 

 United States, and obtained the appointment of professor in Man- 

 hattan College, New York. Four years later he graduated in med- 

 icine from the University Medical College of New York, and in 

 1874 received the appointment of assistant surgeon In the United 

 States army. Dr. Havard's knowledge of botany has enabled him 



to make many interesting and important discoveries in connection 

 with his official duties in various parts of the country, especially in 

 Dakota, Montana, and western Texas. His description of the nat- 

 ural features of western and southern Texas, published in the Pro- 

 ceedings of the United States National Museum for 1885, gives a 

 detailed account of the distribution of the plants of this interesting 

 re<Hon. and of their economic properties and uses, and is an impor- 

 tant botanical paper containing much information which had not 

 previously been made known. 



