284 THE KINDS OF PLANTS 



H. Plant twining: corolla twisted in bud 



XXI. Convolvulaeece, p. 328 

 hh. Plant not twining: corolla plaited or folded in 



the bud XXII. Solavacece, p. 329 



go. Corolla irregular (nearly regular in verbascum). 



XXIII. Scrophulariacece, p. 331 

 ee. Ovary inferior. 



p. Anthers distinct: fls. not in heads 



XXIV. Caprifoliacece, p. 333 



pf. Anthers syngenesious : fls. in dense heads 



XXV. Composite, p. 334 



a. CRYPTOGAMS. 



I. FILICES. Ferns. 



Herbaceous and leafy plants, ours without stems or trunks 

 above ground, but producing perennial rootstocks : plants flowerless 

 and seedless, but bearing spores in sporangia, the latter collected 

 into sori which are usually borne on the under side or margins of 

 the fronds and which are sometimes covered with an indusiuin.- 

 Most abundant in warm countries, of about 4000 species, of which 

 about 165 are native to the United States. The leaflets of fern- 

 fronds are })i)uice ; the secondary leaflets are pinnules. 



a. Fruit borne in contracted panicles or on specially con- 

 tracted parts of the frond, these parts being devoid 

 of resemblance to green leaves. 

 B. Sporangia large and globose, without a ring of special 



cells running around their margin 1. Osmunda 



bb. Sporangia with a ring of prominent elastic cells run- 

 ning around the margin, and which are concerned 



in the dehiscence (as in Fig. 307) 2. Onoclea 



aa. Fruit borne on the back of green fronds (the fruiting 

 pinnae sometimes narrowed but still leaf-like, as in 

 Fig. 305) : sporangia with a ring of elastic cells. 



b. Sori naked (no indusium) 3. Pohjpodium 



bb. Sori borne under the reflexed margins of the frond. 

 C. Pinna? entire on the lower edge, somewhat trian- 

 gular in outline 4- Adiantum 



cc. Pinnae toothed on both margins, oblong in outline. ..5. Pferis 

 bbb. Sori covered with a distinct scale-like indusium. 



c. Shape of sori oblong 6. Asplenium 



cc. Shape circular, indusium peltate or nearly so 7. Dryopteris 



