162 PRACTICAL BOTANY. 



Flowers all fertile. Fruits top-shaped, covered 

 with little scales or tubercles, many in each head. Leaves 

 linear-lanceolate, bristly-fringed or spiny-toothed. 



Eryngium. 



394. Fruit beset with weak prickles in single rows 

 along the ribs. Involucre of several pinnatilid bracts, near- 

 ly as long as the umbel. Umbels concave, dense in fruit. ; 

 The central flower of each umbellet abortive and dark pur- i 

 pie. Daucus CarotsL, L. 



Fruit smooth 295 



393. Fruit strongly flattened dorsally 296 



Fruit not flattened on the back 303 



396. Fruit single-winged or margined at the junction of 

 the 2 carpels 297 



Fruit double-winged or margined at the edge. 

 Each carpel 3-ribbed, or not rarely 3-winged on the back. 



301 



397. Fruit surrounded with a broad and tumid, corky- 

 margin, thicker than the fmit. Carpels nearly riblelsi-ou 

 the back. Flowers yellow. Involucre none. Involucels 

 bristly. Leaves twice-pinnate ; upper leaves 3-eleft. 



Polytaenia Nuttallii, D. C. 

 Margin not corky 298 



398. Flowers yellow. Involucre and involucels want- 

 ing, or inconspicuous. Stem grooved, smooth. Leaves pin- 

 nately-compound ; leaflets cut-toothed. Root spindle- 

 shaped. Calyx-teeth obsolete. Fastinaca sativa,i}j. 



Flowers white 299 



399. Flowers of 2 sorts, the marginal ones radiant. Pe- 

 tals inversely heart-shaped, those of the outer flowers larger. 

 Plant stout, woolly. Stem grooved. ' Leaflets slightly cor- 

 date. Calyx-teeth minute. Heracleiun lanatuin, JUx. 



Flowers all alike ; 300 



300. Leaves none ; in their place simple, long, terete, 

 hollow petioles, with some cross-partitions. 



Tiedemannia teretifolia, D. C. 

 Leaves simply pinnate, 3- to 11-foliolate. 



Archemora rigida, D. 0. 



