636 



BOTANY 



PART II 



Carpels two. A single pendulous ovule in each loculus. 

 abundant endosperm. 



Seed with 



Family 1. Cornaceae. For the most part shrubs or small trees, rarely herbs. 



Leaves simple, usually decussate. K4, C4, A4, G (2). Fruit, a berry or a drupe. 



Cornus mas, the Cornelian Cherry (Fig. 697), expands its umbels of yello\\ 



(lowers before the leaves appear. Each umbel is subtended by four bracts. The 



inflorescences for the succeeding year are already present in the axils of the leaves 



by the time the fruit is ripe. 

 In Britain two species occur ; 

 C.samjiiiiK'n, the Dogwood, and 

 C. suecica, an arctic and alpine 

 plant which reaches its southern 

 limit in Germany. 



Family 2. Araliaceae. Trees 

 or shrubs with alternate leaves, 

 which are often of considerable 

 size and simple, lobed, or com- 

 pound in shape. Floral formula, 

 Ky ; C5, A5, G(5). Flowers in 

 umbels or heads, often further 

 grouped in a panicle-like in- 

 florescence. The carpels vary 

 in number from 2-5 or more. 



In Britain the only repre- 

 -> 'illative of the family is the 

 Ivy (Hcdera Helix}, a root- 

 elimber. The proper elliptical 

 leaf form reappears on the 

 orthotropous shoots of older 

 plants, which in late summer 

 or autumn bear the flowers. 

 The leaves of the creeping or 

 climbing plagiotropous shoots 



FIG. 697. Cornus mas (J nat. size). 7, Flowering twig. .'. 

 Twig with fruits. -.', Flower seen frcm above. 4, Flower 

 in longitudinal section. ('. !,. enlarged.) 



are lobed and usually have 

 shorter stalks (Fig. 698). Calyx 

 with five, pointed sepals corresponding to the five ribs on the inferior ovary. The 

 corolla is greenish in tint ; the large disc on the upper surface of the ovary attracts 

 the visits of bees. The fruits ripen during the winter and become blackish-blue 

 berries ; these are eaten by birds and in this wav the seeds are distributed. 



Family 3. Umbellifepae. Herbaceous plants sometimes of large 

 size. The stem, which has hollow internodes and enlarged nodes, 

 bears alternate leaves ; these completely encircle the stem with their 

 sheathing base, which is often of large size. The leaves are only 

 rarely simple ; usually they are highly compound. Inflorescence 

 terminal, frequently overtopped by the next younger lateral shoot. 

 It is an umbel, or more frequently a compound umbel, the bracts 

 forming the involucre and partial involucres, or an involucre may be 

 wanting. Flowers white, greenish, or yellow ; other colours are 



