498 



BOTANY 



outer or lower surface is convex. The growing points of tin- short shoots soon 

 become funetionless unless stimulated to activity by the death of the apical bud. 

 The male flowers appear in large numbers at the base of the long shoots of the 

 current year and stand in place of the short shoots. One or several female (lowers 

 arise at the tip of similar long shoots, and each corresponds in position to a shoot 

 of unlimited growth. At the time of flowering they are erect, but are bent down- 

 wards after pollination. The seeds ripen in the second year, and are set free by 

 the separation of the scales of the cone which till then have been closely pressed 

 together. The cones subsequently are shed (Fig. 464). Pinus montaim, a dwarf 

 Pine occurring on mountains ; P. pinea, P. ccmbra, with edible seeds ; P. laricio, 

 Corsican Pine from Austria; P. Pinaster, Maritime Pine from the Mediterranean 

 region ; P. tacda, ]'. .SY/W,//*. Weymouth Pine, P. Lambertiana from N. America. 



Cedrus. Cedars from the forests on Atlas and 

 Lebanon. 



POISONOUS. J a Hi in riixSiiliiiui, Tii.i'aslmccata. 

 OFFICIAL. Pinus sylvestris and other species 

 produce OLEUM TEREBIXTHIXAE and RESIN A : 

 Abies balsamea supplies TEREBIXTHIXA CAXA- 

 Di.xsis ; P. palustris and P. taeda yield THUS 

 AMKRICAXUM ; P. excelsa yields PIX BURGUXDICA; 

 P. sylvestris, etc. PIX LIQUIDA; P. piimilin. OLEUM 

 PIXI ; Juniperus oxycedrus and other species yield 

 OLEUM CADINUM ; Juniperus commit nis, OLEUM 



JUNIPERI. 



Order 4. Gnetinae ( 8 ) 



The only Family in this order is that 

 of the Gnetaeeae, to which only three 

 genera belong ; Ephedra (Fig. 465) leaf- 

 less shrubs of warm dry regions of the 

 Northern hemisphere ; Welwitschia mira- 

 bilis, a monotypic plant from the deserts of 

 2. A South-West Africa ; the widely expanded 

 '' summit of the stem bears after the coty- 

 ledons only a single pair of leaves, which 

 are 1 m. in length and continue to grow at their bases ; Gm'tinu 

 (Fig. 466), tropical trees or climbers with pairs of broad, reticulately 

 veined leaves. These genera, while differing widely in appearance, 

 agree in possessing opposite leaves (in Ephedra reduced to scales), 

 in the development of vessels in the secondary wood, the absence 

 of resin canals, and in the presence of a perianth to the flowers which 

 are usually dioecious (Fig. 467). 



These points of agreement with both Gymnosperms and Angio- 

 sperms make the group in many ways an intermediate one between 

 the two classes. The development of the sexual generation in the 

 three genera is as various as their external habit. 



The microspores in their development and germination show no differences from 

 those of other Gymnosperms. The macrospores of Ephedra and Welwitschia have 



FK;. 465. Kphedm altissima. 1. Habit 

 of a male inflorescence, 

 inflorescence with unripe 



(5 nut. si/e.) 



