KEY TO THE ORDERS. 



Subkingdom PTERIDOPHYTA. 



Plants without flowers or seeds, but producing spores each of which, on 

 germination, develops into a flat or an irregular prothallium. The prothallia 

 bear the reproductive organs (antheridia and archegonia). As a result of 

 the fertilization of an egg in the archegonium by a sperm produced in the 

 antheridium a fern or an allied plant is developed. 



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 Leaves broad entire or dissected. (Fern-like plants.) 

 Spores of one kind, minute, borne in sporangia. 



Vernation straight or inclined ; eusporangiate, the sporangia ringless, 

 leathery, opening by a transverse slit, arranged in spikes or panicles. 



Order i. Ophioglossales. i 

 Vernation circinate ; leptosporangiate, the sporangia membranous, pro- 

 vided with a ring which opens elastically. Order 2. Filicales. i 

 Spores of two kinds, minute microspores and larger macrospores, borne 

 in sporocarps ; leaves filiform or quadrifoliate. Order 3. Salviniales. 5 

 Leaves scale-like or awl-like. (Moss-like or rush-like plants.) 



Sporangia in an apical cone, borne under peltate scales : stems hollow, 



rush-like. Order 4. Equisetales. s 



Sporangia in the axils of small or leaf-like bracts : stems solid. 



Leaves awl-like, often much elongated, borne on a short corm-like cau- 



dex : aquatic plants. Order 5. Isoetales. s 



Leaves narrow or scale-like, flat, borne on erect or creeping stems : ter- 

 restrial plants. Order 6. Lycopodiales. 6 



Subkingdom SPERMATOPHYTA. 



Plants with flowers which produce seeds. Microspores (pollen-grains) 

 borne in microsporangia (anther-sacs) develop each into a tubular prothal- 

 lium; a macrospore (embryo-sac) develops a minute prothallium, and to- 

 gether with the macrosporangium (ovule) in which it is contained, ripens 

 into a seed. 



Ovules and seeds borne on the face of a bract or a scale : stigmas wanting. 



Class I. Gymnosperm^e. 7 

 Ovules and seeds in a closed cavity (ovary) : stigmas present. 



Class 2. Angiosperm.s;. i i 

 I. Gymnospermae. 



Staminate and pistillate flowers both in aments ; perianth none ; trees or 

 shrubs with needle- or scale-like leaves. Order 7. Finales. 7 



Staminate flowers in aments ; pistillate ones single or in pairs ; perianth 

 present, urnshaped ; ours horsetail-like shrubs with jointed branches and 

 leaves reduced to sheathing scales. Order 8. Gnetales. 10 



