442 COMPOSITE. Lactuca. 



and imbricated scales, the lowest ovate, the upper successively longer and oblong- 

 lanceolate : pappus of rather rigid light-brownish bristles. 



Gravelly hills, or in sand, Mono Lake (Bolander), and through the western part of Nevada, 

 near the northern borders of which it was first collected by Nuliall. 



123. LACTUCA, Tourn. Lettuce. 



Head few - many-flowered. Involucre cylindraeeous or sometimes campanulate, 

 seldom thickened at base; the scales thinnish, in two or few series, the outer shorter. 

 Eeceptacle flat, naked. Akenes flat, from broadly oval to lanceolate, the sides few— 

 several-ribbed, the apex contracted and commonly prolonged into a beak, its 

 summit abruptly dilated into a disk which bears the (usually bright white) copious 

 pappus of very soft and fine uniform and merely denticulate capillary bristles, falling 

 separately. — Leafy-stemmed herbs, glabrous, or with some bristly hairs, with panic- 

 ulate niiddle-sized heads of yellow or blue flowers. — Benth. & Hook. Gen. PL ii. 

 524. Lactuca & Mulgedium, Cass., DC, Torr. & Gray, PL ii. 495, 497. 



A large, genus in the Old World, represented by a few species in North America ; but no 

 genuine Lactuca (with broad and fiat akenes and long filiform beak) is known on the Pacific side 

 of the continent. The only Californian species being intermediate between true Lactuca and 

 Mulgedium, it is the more expedient to follow Bentham in suppressing the latter genus. 



1. L. pulchella, DC. A foot or two high, wholly glabrous : stem commonly 

 simple, leafy, bearing a loose and naked panicle of several or numerous rather large 

 heads : leaves pale, from oblong-lanceolate to linear, either entire, ruueinately few- 

 toothed, or sparingly pinnatifid : pedicels scaly-bracteolate : involucre cylindraceous, 

 20 — 30-flowered, the outer scales successively shorter: corollas blue: akenes oblong- 

 lanceolate, rather thick-edged, several-ribbed on each face, minutely scabrous, taper- 

 ing into a rather long stout beak, the upper part of which is pale and less firm in 

 texture. — L. integrifolia, Nutt. Gen. Sonchus pidchellus, Pursh. iS'. Sibiricus, 

 Richardson, not of Linn. Mulgedium pulchellum & hcterophyllum, Kutt. 



Eastern part of the Sierra Nevada, north to Oregon, and east nearly to the Mississippi. Heads 

 three fourths of an inch long. The root is apparently biennial or annual. 



L. LEticor-HiEA (Sonchus leucoplmus, Willd., and Mulgedium leucophecum, DC.) extends across 

 the continent from New England to the coast of Oregon, and may occur in northern California. 

 It is a tall and coarse species, known by its runcinate leaves, ample panicle of rather small heads of 

 pale blue or whitish flowers, rusty-colored pappus, and beakless akenes having only a short neck. 



124. SONCHUS, Linn. Sow-Thistle. ■ 



Head many-flowered. Involucre fleshy-thickened at base, ovoid, conical, or cam- 

 panulate ; its scales more or less imbricated, the outer shorter. Eeceptacle flat, 

 naked. Akenes compressed, oval or oblong, several - many-ribbed or nerved, desti- 

 tute of a beak or neck and of a dilated pappus-bearing disk. Pappus of copious 

 very fine and soft white capillary bristles, most of them somewhat united at base so 

 as to be deciduous together, a few separate and stronger ones sometimes less decid- 

 uous. — Leafy-stemmed and mostly glabrous herbs, generally of coarse aspect, with 

 somewhat corymbose or paniculate heads of yellow flowers. Probably none of them 

 indigenous to this country, but the first and second species, the common annual 

 Sow-Thistles, are weeds almost all over the world. 



1 . S. oleraceus, Linn. Two or three feet high : leaves runcinate-pinnatifid or 

 rarely undivided, beset with short and soft spiny teeth, clasping by a heart-shaped 

 base with acute auricles : akenes minutely rugose-scabrous. 



Waste grounds around dwellings ; but no Californian specimens yet seen. 



