22 Trans. Acad. Sci. of St. Louis. 



12-18 cm. long, grayish-green, penciled with numerous small, short, 

 longitudinal, purple lines, glabrous throughout; stem leaves linear 

 oblong, cylindric or somewhat dorsally compressed, standing at right 

 angle to the stem or the apical, I's-Va slightly recurved, slightly taper- 

 ing to the thick base, apex rounded-obtuse, glabrous and glossy light 

 green, very tenderly succulent, 4.5 mm. wide, 3.5 mm. thick, 1.5-2 cm. 

 long, gradually reduced in the branches to oblong or obovoid; rosettes 

 formed at the base of or on the lower part of the stem, depressed 

 globose, 1.8-3.5 cm. in diameter, dense, of many leaves; leaves very 

 succulent, long oblanceolate to spatulate and biconvex or dorsally- 

 compressed clavate, 3 mm. wide at widest portion, one-half as thick 

 and 1 cm. or less in length, bright light green, finely dotted with 

 purple, gray puberulent in the apical half, especially about the margins 

 of the obtuse apex, glabrous and shining below; flowers solitary in 

 the axils of the bracts on the ultimate branches of the stems, sessile; 

 sepals obliquely spreading, very unequal, succulent, short lanceolate, 

 apex bluntly acute, green like the foliage and bracts, slightly puberu- 

 lent; corolla 8 mm. in diameter, rotately spreading with the tips of the 

 petals slightly recurved, petals white with a short green median line 

 on the dorsal side toward the apex, free, lance-ovate, acute; stamens 10, 

 those opposite the petals adhering to their bases for %-y2 the petal 

 length, those alternate free to the base, all as long as the petals and 

 strongly reflexed, filaments white, anthers pale greenish-yellow; the 

 gland a comparatively large yellowish callous with greenish margin; 

 carpels at first erect, gradually becoming recurved and divergent with 

 development; ovary papillose, finely dotted with purple, tipped with a 

 slender style. — Plate X. 



Collected by C. H. Tliompson, August, 1910, at Pa- 

 chuca, Hidalgo, Mexico, where it grows among rocks and 

 low shrubs on the mountain sides above the town. (M, B. 

 G. No. 260/10/72.) 



This sjDecies has much the habit of Sedastrum Hemsley- 

 anum (Plate XI) and on superficial examination would 

 readily be mistaken for that species but may be readily 

 distinguished ])y the characteristic forms of both its cau- 

 line and rosette leaves. The flowers are identical in 

 form but somewhat smaller in the above described spe- 

 cies. It seems to approach more nearly to Sedastrum 

 Painteri, as described in the monograph, but differs from 

 that species in having neither the flat rosette leaves nor 

 the ''broad half-clasping base" of the cauline leaves. 



The above description is made from plants flowering 

 in the Missouri Botanical Garden in the winter of 1910-11. 



