AGROGENS. 17 



1. Ophioglossum, Adder's Tongue. Fertile frond spicate ; sporan- 

 gia in a longitudinal series on its two opposite margins. 3 gen. ; 20 

 species. O" vulgdium, 2'-10' high ; sterile branch of frond ovate, 

 elliptical, entire, l'-2' long, sessile near middle of stalk, from -which 

 rises the short spicate fertile portion. Wet meadows. Common, cos- 

 mopolitan. O. pendulum, sterile part of frond ribbon-like, much 

 longer than the spike. Pendulous, on trees ; S. Africa. 



8. Botrychium. Fertile branch of frond paniculate. Ehiz. erect, 

 fleshy. Cosmop. B. Lundria, Moonwokt. Small, fleshy; sterile 

 branch pinnate. Europe. Prothallus, Fig. 36. B. terndtum, fleshy, 

 3'-10' high ; sterile part of frond triangular, ternately compound. 

 Grassy shades, U. S. B. virginicum, herbaceous, tender, 6'-18' high, 

 sterile part of frond broad, triangular, ternate, divisions 2-3-pinnate ; 

 fertile long-stalked. Rich soil in wood?, S. States. 3. Helminthos- 

 tachys zeyldnica (dulcis), only species. Ehizome horizontal. Sterile 

 branch of frond trifoliately digitate, pedate ; sterile portion a simple 

 spike with pedicelled tufts of spore-cases arranged in whorls, each whorl 

 terminated with a crest-like appendage. Young shoots edible. Ceylon, 

 Ind , E. Archipelago. 



Ord. 5. Equisetacese. Horsetails. — Parthenogenesis. Fertili- 

 zation. Fls. 9 c? or J^. Described, Lesson VIII. 1 genus ; 25 

 species; all containing silica. Cosmopolitan, but not found in Aus- 

 tralia and New Z. Moist places. Kquisetutn Tehnatela, Fig. 37. 

 E. hyemdle, Scouring Rush, 2°-4° high. E. arvense, 8°-20°'high. 

 E. .yi^rareiCTjTO, Tkee Horsetail, 30° high. Oaracoas, S. Am. Equi- 

 setites, fossil, Carboniferous. 



Ord. 6. Marsileacese (Rhizocarpacese). — Parthenogenesis. Fer- 

 tilization. Fls. 9 d^- Described, Lesson VIII. Fossil in Secondary 

 and Tertiary. 4 genera ; 50 species. 2 Tribes : 



Tribe 1. Salviniaceae — Small, ann., floating in pools or lakes ; Ivs. 

 simple, edges reflexed in vernation. 2 gen. ; 8 or lOspecies : 1. Salvinia 

 nutans, only species. Sporoearps, Fig. 39. Warm countries, com- 

 mon ; rare in U. S. 2, AzoUa, branching, Ivs. imbricate. Several 

 species. A. carolinidna, N. Y. to 111., and S. States. 



Tribe 2. Marsileae. — Small, perennial, Ivs. circinate in vernation. 

 In marshes or inundated places. 2 gen. ; about 40 species. Tem- 

 perate regions, both worlds. 1. Marsilea salvdtrix (mdcropus), Nar- 

 Doo. Lvs. quadrifoliolate, petiolate. Sporoearps edible. Specific 

 name from the fact that the fruit saved a party of explorers from star- 

 vation. Pig. 38. Australia. M. vestitn, similar, lvs. hairy ; Western 

 U. S. M. quadrifoHa, larger, S. W., U. S. 2. Pilularia, Pillwort. 

 Lvs. (or leaf-stalks) quill-shaped ; fr. pill-like. Few species ; in Tas- 

 mania, N. Af., Eur. P. globuldria, Gt. Brit. 



Ord. 7. Lycopodiacese. Club-Mosses. — -Parthenogenesis. Fertiliza- 

 tion. Fls. (;P and (5^ 9. Described, Lesson VIII. Perennial. Mag- 

 nificent fossils. See Lesson XIII. 6 gen. ; near 350 spec. ; 2 Tribes : 



Tribe 1. Isoeteae, Quillworts. — J> 9- Small, acaulescent, 

 aquatic; rhiz. globose, rough, with horny processes (phyllopfldes). 

 Lvs. grass-like. 1 genus, Is6etes, 12 species, cosmop. ; nearly all 

 aquatic; 8 or 10 in U. S. I. lacustris, mt. lakes, N. Bng. and Mid. 

 States. I. melanfypoda, shallow water, wet fields. Western IT. S. 

 L Hystrix, not aquatic; sandy places, Channel Islands. I. malin- 

 vernidna, 2° long, in deep water ; Eur. 



