ANGIOSPERM^, DICOTYLEDONES. 7G7 



fig. 283^); the genera Morina and Fedia have two stamens in each flower, whilst 

 the genus Centranthus (Red Valerian) has only one (see p. 240, fig. 263 -). For a 

 description of the pollen of Compositse see p. 99. The gynaeceum in Valerianacea^ is 

 composed of three carpels, and the ovary is originally 3-locular, but two of the 

 carpels are abortive, and only the third loculus is completely developed. In the 

 other families the ovary is unilocular from the first. The ovule and the seed result- 

 ing from its development is pendulous (see p. 178, fig. 249, and p. 240, fig. 263') in 

 Dipsaceae and Valerianacese, basal (see p. 73, fig. 207 ^) in Compositse. In most 

 cases the calyx remains adnate to the mature fruit and assumes the form of a crown 

 of hairs or bristles, which is termed a " pappus " (see p. 432), or else constitutes a 

 membranous limb. In a later chapter we shall deal with the significance of these 

 structures. In the Dipsaceae the fruit is surrounded by a saccate involucre called 

 an involucel. The alliance is distributed over all parts of the earth; its members 

 flourish both in the tropics and in the arctic regions, and are met with on the sea- 

 shore and by the side of glaciers, in bogs and on arid ground, in shady woods and on 

 sandy steppes. The greatest number are natives of the North Temperate Zone. In 

 the Himalayas several Composites occur at an elevation of 4500 metres. Fossil 

 remains have been found in small quantities in the deposits of the Mesozoic and 

 Tertiary Periods. The number of extant species identified up to the present time is 

 about 10,700. 



Alliance XLVIII. — Campanales. 



Families: Campanulacece, Lobeliacece, Stylidiacece, Goodeniacem. 



Annual and perennial herbs with entire exstipulate foliage-leaves arranged 

 spirally. Flowers in capitula or racemes, or else solitary; actinomorphic or zygo- 

 morphic, hermaphrodite or pseudo-hermaphrodite. Floral-leaves diflferentiated into 

 calyx and corolla. Calyx of one whorl of 3-8 sepals, corolla of one whorl of 

 3-8 petals. The calyx-tube clothes the inferior ovary, and the calyx-limb is in 

 the form of 3-8 comparatively large, green segments which crown the top of the 

 ovary. The petals are joined. The gynaeceum is composed of 2-5 connate carpels; 

 the ovary is inferior and 2-5 locular. The ovules are numerous, and are borne on 

 axile placentas. The androecium consists of one whorl of 3-8 stamens, which are 

 attached to the bases of the petals. The filaments are free; in the young flower 

 the anthers are in close contact, forming a tube surrounding the style (see p. 360, 

 figs. 302 ^°> ^^). Sometimes they are connate, and in that case the tube persists even 

 when the flower begins to fade. The pollen is adhesive. The fruit is a capsule 

 (see fig. 340 \ p. 448). 



All the Campanales have laticiferous tubes running through them, and in 

 several species the leaves and stems are copiously supplied with latex. The flowers 

 are actinomorphic in Campanulaceae, zygomorphic in the other families. In the 

 Stylidiace^, only two of the stamens develop pollen capable of eflTecting fertilization, 

 whilst three stamens are abortive; in the other families all the stamens produce 



