CONIFERAE : THE SCOTS PINE 



307 



The chief comparative interest of such a plant as the Scots Pine 

 Has not so much in the form and structure of the sporophyte-plant, 

 as in the details of its propagation. This is carried out, as in the 

 Angiosperms, by organs grouped as Flowers, which are male or female. 

 In the Scots Pine these may be borne on the same tree, though often 

 on distinct branches. The female flower, pink and succulent at 

 pollination, matures into the hard woody coiie, from which the name 



Fig. 249. 

 Radial section of Pine stem, at the junction of wood and bast. Pliloem to 

 the left, xylem to the right. s = autuinn tracheides. / = bordered pits. c = 

 cambium. y = sieve-tubes. i'i = sieve pits, /m — tracheidal medullary ray cells. 

 sm = medullar>' ray cells in the wood containing starch. SM!' = the same in the 

 bast. £Hi — meduilarv ray cells w-ith albuminous content. ( x 2+0.) (.\fter 

 Strasburger.) 



Coniferae is derived (see Fig. 246, p. 304). When ripe it consists of a 

 central axis bearing in a complex spiral numerous woody ovuliferous 

 scales. As the cone ripens the scales turn back, and two seeds may 

 be seen freely exposed on the upper surface of each. When fully 

 ripe each seed separates from the scale, together with a thin film of 

 superficial tissue, which on detachment helps to float it away on 

 the breeze. The seed is protected by a seed-coat, covering a bulky 

 endosperm, with a large embryo enclosed in it, which has many 

 cotyledons, plumule and radicle. The seed is thus " albuminous," 



