1228 CAKDUACEAE 



or less, the others soon reduced to one-third the length, suberect, subulate-linear, sessile 

 and bract-like ; both set below the middle with long slender subremote subulate teeth : 

 involucres broadly hemispherical ; bracts nearly of the same length but of many series, 

 linear-subulate, flat, and appressed, the upper third slender, bristle-like and spreading : 

 rays 3 cm. long, tapering below, light violet, blue or white : disk-flowers very numerous : 

 pappus becoming ferruginous in the herbarium : alveolae deep and pronounced. 

 In low coastal pine lands, Florida. Summer. 



98. Aster Chapmanii T. & G. Stems rigid, arising from a short caudex, glabrous, 

 usually with few slender or nearly filiform branches above : leaves mainly crowded on the 

 caudex, 1-3 dm. long, glabrous, the linear or linear-spatulate blades longer or shorter than 

 the slender petiole-like base, entire, obscurely nerved in drying ; lower cauline-leaves 

 nearly like the basal, the upper gradually reduced to subulate-filiform erect scales, and 

 subulate on the branches : heads few, solitary at the ends of the branches : involucres cam- 

 panulate, 7-8 mm. high ; bracts firm, oblong-lanceolate to broadly linear and linear-oblan- 

 ceolate, erect, acute, sometimes abruptly pointed : ray-flowers numerous ; ligules 1.5-2 cm. 

 long, violet : achenes glabrous. 



In pine-land swamps, western Florida. Fall. 



99. Aster tenulfolius L. Perennial, glabrous and fleshy. Stem 3-6 dm. tall, flex- 

 nous, striate, at least when dry, sparingly and loosely branched : cauline leaves linear, 5- 

 15 cm. long, entire, sessile, or slightly clasping at the base, the lowest lanceolate-linear, 

 those of the branches minute, scale-like, appressed : heads rather few, 12-25 mm. broad, 

 terminating the branches : involucre turbinate, about 8 mm. high ; bracts lanceolate, 

 acuminate or mucronate, glabrous, green on the back or tips, appressed, imbricated in 

 about 5 series, the outer shorter : ray-flowers numerous ; ligules longer than the pappus, 

 pale purple or nearly white : pappus tawny, achenes hispid-pubescent, 5-nerved. 



In salt marshes, coast of Massachusetts to Florida. Summer and fall. 



100. Aster exilis Ell. Annual, glabrous, fleshy. Stem 3-12 dm. tall, slender, 

 usually much branched, the branches usually divergent : cauline leaves linear to linear- 

 lanceolate, 2-10 cm. long, entire, sessile, acute or acuminate, or the lower narrowly oblong, 

 6-8 mm. wide, usually petioled, those of the branches subulate : heads numerous, panicled, 

 about 1 cm. broad : involucre campanulate, about 6 mm. high ; bracts linear-subulate, ap- 

 pressed, imbricated in 3 or 4 series : ray-flowers mostly fewer than those of the disk ; 

 ligules purplish, about 4 mm. long, longer than the pappus : achenes somewhat pubescent. 



In moist or wet soil, especially in saline situations, Kansas to Texas, South Carolina and Florida. 

 Summer and fall. 



101. Aster subulatus Michx. Annual, glabrous and fleshy. Stems 3-18 dm. tall, 

 paniculately branched, flexuous above, slightly angled, sometimes 25 mm. in diameter at 

 the base, but usually smaller : cauline leaves linear-lanceolate, 5-8 cm. long, acute, entire, 

 sessile by a broad or slightly clasping base, those of the branches very small and subulate : 

 heads numerous, 6-10 mm. broad : involucre campanulate, or at length hemispheric, 4-6 

 mm. high ; bracts linear-subulate, green, imbricated in 3 or 4 series, the outer shorter : 

 ray-flowers 20-30, more numerous than the disk-flowers ; ligules purplish, scarcely exceed- 

 ing the nearly white, soft, copious pappus : achenes compressed, minutely pubescent. 



In salt marshes, coast of New Hampshire to Florida. Summer and fall. 



102. Aster spinoaus Benth. Stem woody at the base, divided into striate pliable 

 bright green branches, 1-2.5 m. tall, these branches paniculate : leaves inconspicuous, those 

 of the main branches linear or linear-spatulate, mainly 2-4 cm. long, those of the branchlets 

 reduced to subulate scales or obsolete, all or some of them with soft subulate spines in or 

 above their axils : heads scattered : involucres turbinate, 4-4.5 mm. high ; bracts lanceolate- 

 subulate, attenuate : ray-flowers few ; ligules about 4 mm. long, white : achenes glabrous. 



In moist grounds or on banks of streams', Texas to southern California and Mexico. Summer 

 and fall. 



52. MACHAERANTHERA Nees. 



Annual, biennial or perennial caulescent branching herbs. Leaves alternate : blades 

 serrate or pinnatifid, the teeth or lobes usually bristle-tipped. Heads radiate. Involucre 

 of many series of imbricated bracts with herbaceous or foliaceous tips. Eeceptacle pitted, 

 the pits with toothed or lacerate edges. Ray-flowers pistillate, numerous, with violet red 

 or purple ligules. Disk-flowers perfect, the corollas yellow, turning red or brown. Anthers 

 rounded at the base. Stigmas with subulate or lanceolate appendages. Achenes turbinate, 

 pubescent. Pappus of numerous firm unequal rough bristles. 



1. Machaeranthera tanacetifolia (H.B.K.) Nees. Annual or biennial. Stem 3-6 

 dm. tall, glandular-pubescent and often viscid, much branched : leaves numerous ; blades 



