250 



PLANT LIFE. 



few or many bosses, points, or ridges, as in other spores 

 (A-D, fig. 271). In the pines the outer layer of the wall 



Fig. 267. Fig. 269. 



Fig. 267. — Corolla of Alcanna tinctoria slit and laid open, showing almost sessile 

 stamens united with corolla above the middle of tube, s, scale-like outgrowth from 

 corolla. The tube between j and the notches at edge of corolla result from the growth 

 of a ring of tissue beneath the five fundaments of the corolla which produce the five 

 corolla lobes c. Having grown so far, a ring of tissue inside, on which the stamen fun- 

 daments were developing, became involved in this upward growth, and thus the sta- 

 mens were carried up and arise just above j. Magnified 4 diam. — After Berg and 

 Schmidt. 



Fig. 268.— Very young flower of Hypericum perforatum, seen from above, showing 

 s, sepals; /, fundaments of petals ; a,a,n, fundaments of the three stamens, each al- 

 ready with two lateral growing points, the fundaments of branches, appearing ; g, fun- 

 daments of 3 carpels. Compare with figs. 269 and 270. Magnified about 50 diam. — 

 After Frank. 



Fig. 269.— An older stage of fig. 268, showing only the fundaments of stamens, a, and 

 of carpels, g. On the latter at the angles appear the fundaments of the three styles. 

 Many branches of a have begun. Compare fig. 270. Magnified about 50 diam. 

 — After Frank. 



forms two bladdery swellings which make the spore relatively 

 lighter (E, fig. 271). The pollen spores arise in the spo- 

 rangia in fours in each mother cell, as described in ^| 306. 

 (See 'also fig. 264.) They are either dry and powdery when 



