320 



FOURTH GROUP.— SEED-PLANTS. 



is never terminated by a flower but grows on indefinitely at the apex, while it increases 

 proportionately in thickness through the activity of a cambium-ring, and thus developes 

 into a slender cone often reaching a height of from one to two hundred feet or more, 

 and a diameter at the base of from two to twenty feet. The primary axis thus 



largely developed gives off lateral axes 

 of the first order, often periodically in 

 terminal rosettes (false whorls) or more 

 irregularly distributed, and these branch 

 in their turn in a similar manner; as 

 a rule every parent-axis grows more 

 vigorously than its lateral axes, and 

 therefore as long as the primary axis 

 continues to grow with its accustomed 

 strength the collective form of the branch- 

 system is that of a raceme with a conical 

 or pyramidal outline. It is the branch- 

 ing, almost entirely suppressed in the 

 Cycadeae, which gives the Coniferae 

 their peculiar character and beauty, the 

 more so because the leaves with few ex- 

 ceptions are small and inconspicuous, a 

 sort of clothing for the branches in the 

 general impression made by the plants. 

 The branching is always axillary, but 

 the Coniferae unlike the Angiosperms 

 ■are far from forming buds in all the leaf- 

 axils ; in the Araucarieae and some 

 species of Taxus, Abies and others it 

 is only or chiefly the last leaves of a 

 year's growth that form branches, which 

 then develope vigorously; va Juniper us 

 communis there are buds in the axils 

 of most leaves, but few of them de- 

 velope ; in Pinus sylvestris and its allies 

 shoots are formed only in the axils of the 

 scale-leaves, which are borne throughout 

 on the primary stem and the persistent 

 woody branches, and these shoots con- 

 tinue very short (spurs) and produce 

 each two, three or more foliage-leaves 

 (tufts of needles), from the axils of which no lateral shoots arise ; in Larix, Cedrus, 

 and Gingko buds are formed in the axils of many but not nearly all the foliage-leaves, 

 and some of them elongate rapidly and serve for the development of the main branch- 

 system, while others (the spurs) remain short and form every year a new rosette of 

 leaves without lateral buds ; even in Thuja and Cupressus, which are marked by their 

 copious branching, the number of the small leaves is much greater than that of the 



median longitudinal se^ 



FIG. 250. Pinns pic 

 seed with the niicropylar extremity at y. 

 niination and protrusion of the root. /// conclus 

 after absorption of the endosperm (the seed was n 



of the 

 of ger- 

 of germination 

 deep enough in 



the soil, and was therefore carried up by tlie cotyledons on the elon- 

 gation of the stem), vi shows the ruptured seed-coat .f. .ff shows the 

 endosperm e after removal of one half of the coat. C is a longitudinal 

 section of the endosperm and embryo. Z) is a transverse section of 

 the same at the commencement of germination, c denotes the coty- 

 ledons, 71/ the primary root, -ir the embryo-sac forced outwards by the 

 root (ruptured at x in B), he hypocotyledonary portion of the axis, <<' 

 secondary root, r red membrane inside the hard seed-coat. 



