Subkingdom SPERMATOPHYTA. 



Seed-bearing Plants. 



Plants producing seeds which contain an embryo formed of one or 

 more rudimentary leaves (cotyledons), a stem (hypocotyl, radicle), and a 

 terminal bud (plumule), or these parts sometimes indifferentiated before 

 germination. Microspores (pollen-grains) are borne in microsporanges 

 (anther-sacs) on the apex or side of a modified leaf (filament). The macro- 

 sporanges (ovules) are borne on the face of a flat or inrolled much modi- 

 fied leaf (carpel) and contain one macrospore (embryo-sac) ; this develops 

 the minute female prothallium, an archegone of which is fertilized by 

 means of a tube (pollen-tube), a portion of the male prothallium sprouting 

 from the pollen-grain. 



There are two classes which differ from each other as follows : 



Ovules and seeds borne on the face of a scale ; stigmas none. Class i. GYMNOSPERMAE. 

 Ovules and seeds contained in a closed cavity (ovary) ; stigmas i or more. 



Class 2. ANGIOSPERMAE. 



Class I. GYMNOSPERMAE. 



Ovules (macrosporanges) naked, not enclosed in an ovary, this repre- 

 sented by a scale or apparently wanting. Pollen-grains (microspores) di- 

 viding at maturity into two or more cells, one of which gives rise to the 

 pollen-tube (male prothallium), which directly fertilizes an archegone of 

 the nutritive endosperm (female prothallium) in the ovule. 



The Gymnosperms are an ancient group, first known in Silurian time. They became 

 most numerous in the Triassic age. They are now represented by not more than 450 

 species of trees and shrubs. 



There are three orders, Finales, Cycadales and Gnetales, the first of which is repre- 

 sented in our area by the Pine and Yew Families. 



Family i. PINACEAE Lindl. 

 Pine Family. Conifers. 



Resinous trees or shrubs, mostly with evergreen narrow entire or scale- 

 like leaves, the wood uniform in texture, without tracheae, the tracheids 

 marked by large depressed disks, the pollen-sacs and ovules borne in 

 separate spikes (aments). Perianth none. Stamens several together, 

 subtended by a scale ; filaments more or less united ; pollen-sacs (anthers) 

 2-several-celled, variously dehiscent ; pollen-grains often provided with 

 two lateral inflated sacs. Ovules with two integuments, orthotropous or 

 amphitropous, borne solitary or several together on the surface of a scale, 

 which is subtended by a bract in most genera. Fruit a cone with numer- 

 ous, several or few, woody, papery or fleshy scales ; sometimes berry-like. 

 Seeds wingless or winged. Endosperm fleshy or starchy, copious. Embryo 

 straight, slender. Cotyledons 2 or several. About 25 genera and 240 

 species of wide distribution, most abundant in temperate regions. 



30 



