104 ELEMENTARY BOTANY. 



Devonian and Carboniferous Ages. Some of them (Lepido- 

 dendron, etc., Fig. 131), were of gigantic size, but the group to 

 which they belonged became extinct in the Permian Period. 

 Several species of Lycopodium occur in the United States. 

 Many species of Selaginella, which are mostly tropical, are 

 cultivated for ornament. 



The Equiseta and Club-mosses may be found in wet, sandy places and in 

 damp, rocky woods. Take a single specimen of each, and after close exam- 

 ination make notes and figures illustrating the general structure. The spores 

 and the minute anatomy cannot be examined without the aid of the micro- 

 scope. Herbarium specimens of the species can be made as in case of the 

 flowering plants (p. 105). 



20. The lower group of the Phenogamous plants includes 

 the Gjminosperms (Gr. gymnos, naked ; sperma, seed), as Cy- 

 cads, Pines, Firs, etc. They rank above the Cryptogamous 

 plants but are closely allied to them. They are characterized 

 by having (as the name indicates) naked ovules, that is, ovules 

 not enclosed in an ovary. The seeds have in many cases sev- 

 eral cotyledons. The species are terrestrial, chlorophyll-bear- 

 ing, and with some exceptions trees, often very large. Bor- 

 dered pits are found in their woody tissue and are peculiar 

 to this group. Many of the representatives produce turpen- 

 tine containing dissolved resin. The family Pinaceas (including 

 the Pines, Firs, Balsams, Larches, Cedars, Big Trees of Cali- 

 fornia, etc.) is of great economic importance, furnishing, be- 

 sides turpentine and resin, a large quantity of lumber suitable 

 for a great variety of uses. 



21. The other group of flowering plants, namely the An- 

 giosperms (Gr. angios, vessel), is distinguished from the pre- 

 ceding by having the ovules enclosed in seed-vessels or ovaries. 

 It is to this group that the outline of Organography and much 

 of the practical work suggested in preceding pages in the main 

 applies. The two divisions, Monocotyls and Dicotyls, have been 

 frequently mentioned and contrasted. The morphological and 

 physiological development is higher than that of the preceding 

 groups. They are also of greater economic importance, fur- 

 nishing an exceedingly large variety of useful products. 



