594 BOTANY part ii 



three loculi of the ovary are almost completely filled by numerous 

 ovules and projecting fleshy placentee. The fruit is a spherical or 

 elongated berry, not unfrequently of an enormous size. Its firm, some- 

 times hard exocarp (then termed a pepo) usually encloses a succulent 

 mesocarp derived chiefly from the placentae. The seeds are large and 

 flat, and without endosperm. 



Geographical Distribution. — The Cucurbitaceae comprise for the most part 

 plants of the Tropical Zone, thriving best in the dry open districts. Various 

 speeies are cultivated for the sake of their fruit, e.g. the Pumpkin (Cucurbits, Pepo), 

 the Cucumber (Oucumis sativus), the Musk-melon (Cucumis Melo), the Water- 

 melon (Gitrullus vulgaris), etc. 



Poisonous. — Bryonia dioica (Fig. 587) and B. alba, hirsute tendril-climbers 

 with tuberous roots, lobed leaves, and comparatively small berries, which in the 

 former species are red, in the latter white. 



Officinal. — Citrullus ColocyntAis, a herb somewhat resembling the cucumber, 

 native of the African and Arabian deserts, yields Pulpa Colooynthidis. 



Order 10. Aggregatae 



Flowers epigynous, actinomorphic or zygomorphic, constructed after 

 the formula K5, C(5), A5, G(2) ; calyx RUDIMENTARY ; stamens in- 

 serted on the corolla ; anthers usually adherent (syngenesious) : 

 ovary unilocular, with one ovule. Fruit indehiscent. Inflorescence 

 a capitulum, surrounded by an involucre. 



The capitate inflorescence is the most distinctive characteristic of the 

 Aggregatae. The margin of the expanded axis of the inflorescence is 

 occupied by numerous hypsophylls, while its whole upper convex or 

 concave surface is thickly beset with small flowers (florets), which 

 are frequently given off from the axils of reduced subtending bracts 

 or scales (palese). In its general appearance the whole inflorescence 

 resembles a single flower, particularly when the marginal flowers are 

 larger than the central, and form a sort of corolla about them. 



In the united anthers and in the occurrence of septated latex tubes the Compo- 

 sitae show a relationship with the Campanulinae, whilst the Dipsacaceae, on the 

 other hand, are apparently connected by intermediate forms with the Valerianaceae. 



Family Dipsaeaeeae. — Flowers with epicalyx, usually zygo- 

 morphic ; corolla four- to five-lobed, imbricate in the bud ; stamens 

 four, with free anthers ; style simple ; ovules suspended ; seeds 

 with endosperm. Leaves opposite (Fig. 588). 



Herbs with simple or pinnate leaves and many-flowered, flat or 

 convex capitula whose marginal flowers are frequently larger than the 

 central. The possession of an epicalyx consisting of united bracteoles 

 is characteristic of the flowers of this family. The true calyx is 

 rudimental, represented only by teeth or bristles. By the cohesion of 



