COMPOSITE 



115 



First leaves simple, radical, entire or slightly serrate, alternate, 

 petiolate, exstipulate, broadly lanceolate, subacute, hirsute, green, 

 trinerved ; petiole very long, covered with stiff bristles, deeply 

 channelled on the upper side. 



Helianthus anmms, L. 



Achene obovoid, much compressed, but thickest near the apex, 

 tipped with the persistent base of the flower, glabrous, brown, striped 

 or mottled with grey ; outer coat thin, membranous ; inner thick- 

 ened or subwoody at the lateral edges. 



Seed obovate, much flattened but obtusely tetragonal, conforming 

 in outline to the achene, but shrunk when dry ; testa thin, mem- 

 branous, white, closely applied to the seed. 



Endosperm absent. 



Embryo large, straight, conforming in outline to the seed ; coty- 

 ledons obovate, obtuse, entire, plano-convex, closely applied to each 

 other face to face, colourless ; radicle short, turbinate, obtuse. 



Helianthus cucumerifolius, A. Gray (fig. 459). 



Achene differs from that of H. amiuus in being 

 much smaller, oblong-obovate, and obtusely tetra- 

 gonal with the lateral angles smaller and more 

 obtuse, while the apex is more truncate, and some- 

 times depressed, causing an emargination of the 

 cotyledons. 



Primary root slender, colourless, with a few 

 fibrous lateral rootlets. 



Hypocotyl herbaceous, terete, glabrous, about 

 3 cm. long, 1 mm. thick, brownish-green. 



Cotyledons subsessile and semiamplexicaul, 1*2- 

 1-5 cm. long, over 5 mm. wide, obovate-spathulate, 

 rounded at the apex, entire or slightly emarginate, 

 obscurely nerved, glabrous, thin, light green. 



Stem with the first internode 5 mm. long, terete, 

 succulent, green, covered with silky hairs. 



Leaves cauline, opposite, exstipulate, simple, con- 

 nate and clasping the bases of their petioles. 



First pair entire, oblong, obtuse, obscurely tri- 

 nerved, coarsely pubescent on both sides, tapering into the chan- 

 nelled petiole, 2-5 cm. long, 5-7 mm. wide ; petiole 3-5 mm. long. 



Second pair lanceolate-ovate, obtuse or subacute, trinerved, 

 serrulate with gland-tipped serratures, coarsely pubescent above, 

 almost villous beneath, with short petioles. 



i 2 



FIG. 459. 



Helianthus 



cucumerifolius. 



Half nat. size. 



