APETAL^— S ALICACE^ 1 1 5 



following year the highest axillary bud of these branches shoots 

 out, and thus continues the growth of the branch. Thus the 

 Willow -branches are sympodia. Inflorescences : the stamens 

 and carpels do not occur on the same individual, the plant is 

 dioecious. The flowers are arranged in catkins which are 

 erect, not pendulous. Each catkin arises, in July, in the axil 

 of a foliage leaf, on a part of the stem formed during that year. 

 The foliage-leaves fall off in autumn. Consequently, when the 

 catkins burst out in the following year (from March to May), 

 they are seen to be in the axils of fallen leaves on a part of the 

 stem which was produced during the previous year. The inflor- 

 escences (figs. 140, 143) open before the foliage-leaves emerge 

 from their buds. The axis of the inflorescence bears at its base 

 a few scales, and higher up a number of scale-like bracts and 

 axillary flowers. One flower stands in the axil of each bract. 

 The staminate (<?) flower (fig. 141) consists of two stamens 

 (a) and a greenish nectary (n) situated on the base of a bract (d). 

 The stamens have long filaments, extrorse anthers, and sticky 

 pollen. The carpellary ( ? ) flower (fig. 144) is also inserted 

 on a bract (d) ; it consists of a nectary (n) and a syncarpous 

 gynfficium composed of two carpels. The ovary (ov) is stalked, 

 and has one chamber which contains many ovules attached to 

 two parietal placentae. The single short style forks above into 

 a two-armed stigma (sg). The nectary is regarded as part of 

 the flower, and, being inserted below the ovary, the flower is 

 described as hypogynous. Fruit and dissemination. — The 

 fruit is a two-valved capsule which allows the escape of the 

 numerous minute seeds. The seeds are scattered by the wind, 

 and each seed is possessed of a tuft of silky hairs, which forms 

 the sailing mechanism. 



Type II. : POPLARS (Populus). 



Poplar-trees differ from the Willows in having pendulous 

 catkins, staminate flowers with from four to an indefinite 

 number of stamens [some Willow flowers have as many as five 

 stamens], and dry pollen. Moreover, the flowers have no 

 nectaries, though they possess a hypogynous basin-like out- 

 growth, which is regarded as either a disk or as a perianth. 



Pollination of the Willow and Poplar. — The Willow is insect- 

 pollinated, whereas the Poplar is wind-pollinated. In accord 



