ANGIOSPERALE, DICOTYLEDONES. 781 



only been observed in a very few species (e.g. Poterium). In some Dryadacese and 

 Chrysobalaneae the style springs in a curious manner from the base of the ovary 

 (see fig. 438 * 3 ). The fruit is a pod (legume) in Papilionaceae, Caesalpineae, and 

 Mimoseae, and these three sub-families are hence often classed together by botanists 

 under the name of Leguminosae. The fruit of Amygdaleae, Chrysobalaneae and 

 Rubeae is a 1 -stoned drupe, that of Rhamnaceae a 3-stoned drupe. The Agrimoneae 

 and Dryadeae are distinguished by small nut-like fruits, and the Spiraeeae, Saxi- 

 fragaceae, and Crassulaceae have follicles which dehisce at the upper part of the 

 ventral suture. In most of the families above enumerated the seeds contain no 

 endosperm; on the other hand, the thick cotyledons are crammed with reserve 

 materials, and several of these seeds are used as important articles of human food 

 (e.g. beans, peas, lentils, &c.). 



The Crateranthae are distributed in all quarters of the globe and in all latitudes. 

 Caesalpineae and Chrysobalaneae belong chiefly to the tropics, whilst Dryadeae and 

 Saxifragaceae live principally in the arctic regions and on high mountains. The 

 Papilionaceae are found most abundantly in the area of the Mediterranean flora 

 and in the steppes in the south-west of Asia. More than 800 species of the genus 

 Astragalus alone are known to exist in the last-mentioned districts. The Mimoseae, 

 especially the species of the genus Acacia, are represented in Africa and Australia 

 by many characteristic forms. Roseae and Rubeae, e.g. the genera Rosa and Rubus, 

 occur in an astonishing variety of species in Central Europe, whilst the Spiraeeae 

 and Amygdaleae are in like abundance in the west of Asia. Crassulaceae are most 

 abundant at the Cape and in Mexico, but they are also represented by a great 

 number of species of the genus Sempervivum in the mountainous parts of Southern 

 Europe. Rhodiola rosea, which belongs to this family, occurs in the arctic flora, 

 and Sedum repens is found in the Alps at a height of 3000 metres above the sea. 

 Of the Saxifragaceae, Saxifraga oppositifolia reaches the furthest north, it having 

 been met with at the northernmost spot hitherto visited in Franz Joseph's Land, at 

 81 N. Lat. In the Central Alps this Saxifrage is found at an elevation of 3160 

 metres. Fossil remains of Rosacese, Leguminosae, and Rhamnaceae have been identi- 

 fied in the deposits of the Tertiary Period. The number of extant species hitherto 

 discovered amounts to about 10,000. 



Alliance LVIIL Myrtales. 

 Families: Myrtacece, Granatocece, Onagracece. 



Annual and perennial herbs, shrubs, and trees, with entire foliage-leaves. Vena- 

 tion consisting of a main axial strand, with sinuous lateral strands branching 

 pinnately from it. Flowers hermaphrodite, actinomorphic or zygomorphic. The floral- 

 leaves spring from an annular or tubular hypanthium, which is fused with the 

 inferior ovary they are differentiated into calyx and corolla, each of which ecu 

 of a 2-6-merous whorl. The stamens are in 1, 2, or more whorls of 2-6 members 



