

COMPOSITE. (COMPOSITE FAMILY.) 223 



Var. SCOpulorum, Gray. Minute : leaves and scape an inch or less long : 

 head 3 or in fruit even 5 lines high, narrow, few-flowered : outer involucral 

 bracts lanceolate, rather loose ; inner somewhat corniculate. T. Icevigatum, 

 Gray. Highest alpine region of the liocky Mountains in Colorado. 



82. PYRRHOPAPPUS, DC. 



With leafy or (in ours) scapiforra stems, undivided or pinnatifid leaves, and 

 rather large slender pedunculate heads of golden yellow flowers. Our species 

 is rnonocephalous. 



1. P. SCapoSUS, DC. Hirsutulous-pubescent, low and simple: globular 

 tuber sending up a slender caudex, bearing at the surface of the ground a 

 cluster of pinnatifid leaves and scapes of a span or two high: the latter sim- 

 ple and naked, sometimes a bract or small leaf near the base : head seldom an 

 inch high in fruit : calyculate bracts of involucre short and small, subulate ; 

 principal ones obscurely corniculate at tip : flowers citron-yellow : pappus 

 fulvous. P. grandiflorus, Nutt. Prairies of Arkansas to E. Colorado. 



83. LACTUCA, 1 Tourn. LETTUCE. 



Mostly tall herbs, with milky juice, leafy stems, and paniculate heads of 

 yellow, blue, or whitish flowers: involucre glabrous and smooth. Includes 

 Mulgedium. 



# Akenes flat, orbicular to oblong, abruptly produced into a filiform beak of softer 



texture. 



1. L. Ludoviciana, DC. Glabrous, leafy to the open panicle, 2 to 5 feet 

 high : leaves all oblong and auriculate-clasping, 3 or 4 inches long, sinuate-pin- 

 natifid, somewhat spinulosely dentate, more or less bnstly-ciliate, more or less 

 hispidulous-setose on the midrib beneath : flowers yellow : akenes oblong-oval, 

 about equalled by the flliform beak. From Dakota and Wyoming to Iowa and 

 Texas. 



2. L. pulchella, DC. A foot or two high, very glabrous, glaucescent, 

 leafy up to the open panicle : leaves from linear-lanceolate to narrowly oblong, 

 entire or runcinate-dentate, or some lower ones pinnatifid ; cauline sessile, with 



* The Old World genus Sonchus, Tourn., ("Sow-Thistle.") with leafy stems, yellow 

 flowers, and white pappus, hag become extensively naturalized in the' east, and the follow- 

 ing species have appeared within our range : 



* Coarse annuals ; with runcinately or lyrately pinnatifid leaves, beset with soft spinulose 



serratures; upper cauline auriculate-clasping: heads corymbose-paniculate : akenes 

 flat, thin-edged, oblong- obovate 



S. oleraceus, L., has leaves with soft and hardly spinulose teeth ; auricles of the cauline 

 ones acute ; akenes striate-nerved and transversely rugulose-scabrous. 



S. asper, Vill. , has teeth of the leaves longer and more prickly ; auricles of the clasp- 

 ing base rounded ; and akenes smooth, 3-nerved on each side. 



* * Strong-rooted perennial, with deep yellow flowers, and thickish akenes. 

 S. arvensis, L., has stems 2 feet high and naked at the summit ; leaves as before, den- 

 ticulate-spin ulose, cauline partly clasping ; peduncles and involucre more or less glandular- 

 bristly ; heads almost twice as long (1 inch high) ; akenes oblong, about 10-ribbed and 

 ruguloae on the ribs. 



