COMPOSITACEAE (COMPOSITE FAMILY) 225 



II. Most of the leaves on the stem; ray flowers neutral; pappus of 2-6 deciduous 



scales or awns. HELIANTHUS (p. 227) 



HH. Heads less than 2.5 cm. wide; involucre bracts boat-shaped, more or less 



inclosing an outer or ray akene; leaves lanceolate or narrower (except Lago- 



phylla). 



K. Akenes flattened at right angles to the involucre; involucre bracts keeled 



on back; plants mostly viscid-glandular; pappus none except in M. madioides, 



of 5-8 scales. (From madi, the name in Chile.) Madia (TARWEED) 



KK. Akenes not flattened at right angles to the involucre; involucre bracts 



rounded or flattish on the back. 

 L. Pappus none. 



M. Leaves of the stem pinnatifid; leaves of the branches and fascicles entire, 

 spinulose-tipped; involucre bracts spinulose-tipped; disk flowers 10 or more; 

 ray flowers 10 or more; most of the leaves alternate. (Gk. hemi = half, 

 zone = a girdle; the ray akenes are swollen on one side.) Hemizonia 



MM. Leaves all entire, not spinulose-tipped; involucre bracts not spinulose- 

 tipped; disk flowers 1-6; ray flowers 4-6. 



N. Disk flowers 1-2, fertile; akenes slightly hairy; plant 2.5-20 cm. high; 



most of the leaves opposite, 2.5 or less long. W. C. (Diminutive of 



Hemizonia a related genus.) Hemizonella durandii 



NN. Disk flowers 5-6, sterile; akenes smooth; plant 15-75 cm. high; most 



of the leaves alternate, 5 cm. or less long. E. (Gk. lagos = a rabbit, 



phyllon = a leaf. Application not clear.) Lagophylla ramosissima 



LL. Pappus present at least on the disk akenes, of 7-12 scales which are often 



awn-tipped. 



O. Upper leaves spinulose- or gland-tipped; pappus of 7-12 scales, in i whorl, 



often awn-tipped, its scale portion 3 mm. or less long. (See M.) Hemizonia 



OO. Leaves neither spinulose- nor gland-tipped; pappus of about 10 scales, 



in 2 whorls, not awn-tipped, inner whorl about 6 mm. long. U. (Gk. 



achyron = chaff, achaino = an akene; probably referring to the chaff-like 



pappus.) Achyrachaena mollis 



GG. Pappus of 2-6 stout retrorsely-barbed awns; heads 0.8-10 cm. wide. 



BIDENS (p. 228) 

 BB. Rays white or pink. 



P. Involucre bracts almost flat, not inclosing the ray akenes; leaves narrowly linear, 

 margins involute or revolute; heads 12-30 mm. wide; rays 3-6. E. (Gk. ble- 

 pharon = an eyelash; + pappus.) Blepharipappus 



PP. Involucre bracts boat-shaped, inclosing each an outer or ray akene. 

 Q. Heads 12-25 mm. wide; rays 8-13; basal leaves often laciniately lobed or in- 

 cised. E. (Meaning not determined.) Layia glandulosa 

 QQ. Heads 4-12 mm. wide; rays 1-7; leaves all entire or nearly dentate. (See M.) 



Hemizonia 

 AA. Heads rayless, i.e., without ligulate flowers. 



R. Pappus none; heads few-flowered; flowers yellow or greenish, the staminate and 



pistillate often in separate heads; fruit often burlike. 

 S. Leaves broadly lanceolate or wider, often lobed or pinnatifid; heads staminate 



or pistillate or with both kinds of flowers. 



T. Involucre neither tubercled nor spiny; fruit not a bur; staminate and pistillate 

 flowers in the same head; plant merely puberulent or scabrous; lower leaves 

 opposite. E. (Named from Ajuga iva, a plant with a similar odor.) 



Iva (MARSH ELDER) 



TT. Involucre of pistillate heads either tubercled or spiny, making fruit rough or 

 burlike; staminate and pistillate flowers in separate heads; plant either hairy 

 or all the leaves alternate. 



F. & R. EL. FL. 15 



