35. S. rádula, Nutt. Stem and _oblong or obovate-spatulate leaves rigid and very rough, not hoary_, the upper sessile; scales oblong, rigid; rays 3--6; otherwise nearly as in n. 34.--Dry hills, W. Ill., Minn. Kan., and southward. 36. S. Drummóndii, Torr. & Gray. _Stem_ (1--3° high) _and lower surface of the broadly ovate or oval somewhat triple-ribbed leaves minutely velvety-pubescent_, some of the leaves almost entire; racemes panicled, short; scales of the involucre oblong, obtuse; rays 4 or 5.--S. W. Ill., Mo., and southward. [+][+][+][+] _Heads in a compound corymb terminating the simple stem, not at all racemose; leaves mostly with a strong midrib._ [++] Leaves flat, not 3-nerved. 37. S. rígida, L. _Rough and somewhat hoary_ with a minute pubescence; stem stout (2--5° high), very leafy; corymb dense; _leaves oval or oblong_, copiously feather-veined, thick and rigid; the upper closely sessile by a broad base, slightly serrate, the uppermost entire; heads large, over 30-flowered; the rays 7--10.--Dry soil, N. Eng. to Minn., and southward. 38. S. Ohioénsis, Riddell. _Very smooth_ throughout; stem wand-like, slender, leafy (2--3° high); _stem-leaves oblong-lanceolate, flat_, entire, obscurely feather-veined, closely sessile; the lower and radical ones elongated, slightly serrate toward the apex, tapering into long margined petioles; head numerous, on smooth pedicels, small, 16--20-flowered; the rays 6 or 7.--Moist meadows or prairies, W. New York to Ind. and Wisc.--Root-leaves 1° long; the upper reduced to 1--2´, with rough margins, like the rest. [++][++] _Leaves somewhat folded, entire, the lower slightly 3-nerved._ 39. S. Riddéllii, Frank. _Smooth and stout_ (2--4° high), _very leafy_, the branches of the dense corymb and pedicels rough-pubescent; _leaves linear-lanceolate, elongated_ (4--6´ long), acute, partly clasping or sheathing, _mostly recurved_, the lowest elongated-lanceolate and tapering into a long keeled petiole; _heads very numerous_, clustered, 20--30-flowered; the rays 7--9.--Wet grassy prairies, Ohio to Minn. and Mo.; Ft. Monroe, Va.--Heads larger than in the last, 2--3´´ long. Stem-leaves upright and partly sheathing at the base, then gradually recurved-spreading. 40. S. Houghtònii, Torr. & Gray. _Smooth; stem rather low and slender_ (1--2° high); _leaves scattered, linear-lanceolate, acutish_, tapering into a narrowed slightly clasping base, or the lower into margined petioles; _heads few or several_, 20--30-flowered; the rays 7--9.--Swamps, north shore of Lake Michigan; Genesee Co., N. Y. July, Aug.--Leaves rough-margined, 2--5´ long, 2--4´´ wide, 1-nerved, or the lower obscurely 3-nerved above; veins obscure. Heads large, nearly ½´ long. Scales of the involucre obtuse.