SECT. II 



PHANEROGAMIA 



553 



splits into four valves. Tlie Oaks, Qucrcus pedunmlata (Figs. 527, 528) and 

 Quercus sessilijiora, are tlie largest deciduoiis trees of European woods. Leaves 

 oval, margins siuuately lobed ; those of Q. sessilijiora with longer stalks. The 

 pendulous male inflorescences sjiring at the time that the new foliage is ex- 

 panding from axillary buds of the shoot of the preceding year or from the lowest 

 buds of the shoot of the current year ; flowers 

 solitary, consisting of a perianth of 5-7 segments 

 and 6-12 short stamens. Female inflorescences 

 erect, few-flowered, in the axils of the upper 

 leaves of the shoot of the current year. Flowers 

 solitary ; in Q. pedunculata with long stalks, 

 in Q. sessilijiora sessile. Each flower is invested 

 by a cupule (Fig. 525, C), which is at first incon- 

 spicuous, but is fully developed on the ripe 

 fruit. 



The Beech yields firewood, tar, and pyro- . 

 ligneous acid ; the Oak provides a valuable 

 timber, a bark containing tannin used in tanning, 

 and cork from the Cork- oak. 



Official. — The galls produced on the 

 young twigs of Quercus infectoria as a result 

 of puncture by the Gall-wasp, Cynips tinctoria ; 

 Tannic Acid is obtained from these. 



Order 4. Salieiflorae 



Family Salieaeeae. — Trees and shrubs 

 with simple, alternate, stipulate leaves. 

 Flowers in dioecious catkins, usually 

 develoi^ed before the leaves. Both male 

 and female flowers are naked and stand 

 in the axils of bracts. More or less 

 developed scale-like development of the 

 disc or floral receptacle. Ovary of two 

 carpels, unilocular. Fruit, a capsule 

 containing numerous, parietal seeds. 

 Seeds without endosperm ; seed - coat 

 with a tuft of hairs. 



Fig. 529.— SaKx viitdnalis. A, Flower 

 ing male twig (nat. size) ; B, male 

 flower with subtending bract (mag- 

 nified) ; C, female inflorescence ; 

 D-E, female flowers (magnified) ; F, 

 fruit (nat. size) ; G, the same mag- 

 nified ; H, seed (magnified). 



This family is mainly represented in the 

 north temperate zone. Salix, Willow, and 

 Pojjulus, Poplar, are the only genera. Salix 

 has erect catkins and is adapted for pollination 



by insects ; in relation to this, nectar is secreted by small scales at the base 

 of the flower. Male flowers scented, pollen sticky. The number of stamens varies 

 from 2 to 5 in the different species. Bracts entire (Fig. 529). Willows occur 

 commonly by the banks of streams where their shortly stalked, narrowly lanceolate 

 leaves give them a characteristic appearance. Some species are among the more 

 abundant plants of high northern latitudes ; they have subterranean, creeping 

 stems, only the young shoots projecting from the soil. Popidus has anemophilous 



