6(3). Perennial with numerous prostrate or loosely decumbent stems 



4. H. Greggii. 



6. Annual with typically erect stems (7) 



7(6). Throat of corolla pubescent just below the limb; corolla lobes narrow and 

 acute; mericarps coarsely strigose 5. H. procumbens. 



7. Throat of corolla glabrous; the shallow corolla lobes broad and rounded; 



mericarps glabrous or at most puberulent 6. H. indicum. 



1. Heliotropium molle (Torr.) I. M. Johnst. 



Low perennial, occurring in colonies; stems decumbent, loosely branched, 1-3 

 dm. long, developing anew each year from the root or from a small weakly devel- 

 oped caudex, gray or tan, appressed hispid-villose; leaves numerous, with a petiole 

 1-3.5 cm. long, densely hispid-villose with appressed hairs, the margins moderately 

 to coarsely crenate and visually crisped, apex acute to obtusish, base usually broadly 

 asymmetric; inflorescence terminal on the leafy stems or opposite leaves, consisting 

 of 2 or 3 densely flowered scorpioid cymes borne at the apex of a naked peduncle 

 2-4 cm. long; calyx subsessile, at anthesis 2-3.5 mm. long, the lobes at maturity 

 3-5 mm. long, linear-lanceolate, hairy, embracing the fruit; corolla white or slightly 

 stained with purplish, in throat yellow, total length 6-10 mm. long, funnelform, the 

 lobes rounded and separated by well-developed plaited inflexed sinuses; fruit dry, 

 ovoid-globose, 3.5-4 mm. high, dorsiventrally 4.5-5 mm. long. 



Growing in valley soils, on flats, usually in places where water collects and stands 

 for a short time after rain storms, and most commonly in places in the vie. of 

 Upper Cretaceous outcrops, in Tex., only from Brewster Co. and from along the 

 Rio Grande in w. Presidio Co., Apr.-Sept.; also Coah. and Chih. 



It is worthy of note that another Texan species of this genus, which also grows 

 on clay flats in places where there is a shallow pooling of water after rains, likewise 

 has what appears to be buoyant corky tissue developed in the mericarp. This corky 

 tissue in the mericarps of H. molle and H. glabhusculum may be useful in the 

 dissemination of the fruit by water and may be adaptations for the specialized 

 habitat these plants aff'ect. 



2. Heliotropium glabriusculum (Torr. ) Gray. Cola de alacran. 



Perennial, forming colonies; stems usually several, springing from the root crown 

 or from a small caudex, renewed annually, grayish strigose with the hairs all mal- 

 pighiaceous, loosely decumbent and branched, 1-3 dm. long; leaves numerous, 

 green, minutely and abundantly dotted, firm, usually glabrous except on the petiole 

 and along the prominent midrib on the lower surface, the margin weakly revolute 

 and usually more or less evidently crisped, apex acute, base narrowed into a petiole 

 1-6 mm. long; inflorescence terminal on the leafy stems and branches, consisting 

 of 2 or sometimes 3 densely flowered scorpioid cymes borne clustered on a naked 

 peduncle 1-3 cm. long; flowers fragrant; calyx sessile, 2-3 mm. long, the lobes 

 lanceolate, attenuate, moderately unequal, with a few malpighiaceous hairs down 

 the middle line and sparingly ciliate with simple hairs on the margin; corolla white 

 with a greenish-yellow throat when fresh, becoming cream-colored with a purplish 

 throat when dry, 4-5.5 mm. long, the sinus between the short corolla lobes simple, 

 closed with neither plaits nor lobules; fruit grayish from a dense pubescence of 

 minute simple hairs. Heliophytum glabriusculum Torr. 



Growing on valley soils, usually on clay in limestone areas, and particularly in 

 places subjected to temporary flooding after rain storms, in Tex. it has been col- 

 lected most frequently in s. Brewster and s. Pecos cos., but it is also known from 

 Val Verde, Maverick, Webb and McMuUen cos., May-Aug.; from Tex. s. to e. 

 Dgo. and n. Zac. 



The malpighiaceous hairs readily distinguish H. glabriusculum. 



1385 



