562 BOTANY 



7. Phaseoloideae. — Climbing plants ; leaves usually imparipinnate, frequently 

 ternate. Physostigma {Officinal) ; Phaseolus. 



Geographical Distribution. — The large family of the Papilionaceae is not 

 exclusively confined to any zone. The steppes of Western Asia are especially rich 

 in Papilionaceous plants, represented in particular by shrubby species of Astragalus, 

 from which gum-tragacanth is obtained. The leaflets of the pinnate leaves of the 

 Tragaeanth shrubs eventually fall off from the main stalks, which remain attached 

 to the steins, and resemble long thorns. The gum is produced by the disorganisa- 

 tion of the stem-parenchyma, and exudes as a viscous fluid when incisions are 

 made in the stems. The most important cultivated plants are — Pisum sativum, 

 the Pea ; Phaseolus vulgaris, the common Kidney or French Bean ; Vicia Faba, the 

 Broad Bean ; Ervum Lens, the Lentil ; Dolichos Soya, the Soja (Soy) Bean oi 

 Japan and China ; Indigofera species, Indigo (Tropics). 



Poisonous. — The seeds of the Laburnum, Oytisus Laburnum (Fig. 539), a 

 small tree indigenous to the Alps, sometimes cultivated in gardens. It is character- 

 ised by its ternate leaves, and by its racemes of large, yellow flowers and many- 

 seeded legumes. The other species of the same genus, 0. alpinus, 0. purpureus, 

 0. Weldini, C. biftorus, have also toxic properties. Goronilla varia (Fig. 538), an 

 herbaceous plant with umbels of rose-coloured flowers, is also considered poisonous, 

 and the familiar ornamental climber, Wistaria sinensis. 



Officinal. — Astragalus species, from which Tragacantha is obtained. The 

 stolons of Glycyrrhiza glabra, an herbaceous perennial of Southern Europe, con- 

 stitute Licorice Root, Rad. Liquiritiae ; from the roots of the variety glandu- 

 lifera (Russia) Rad. Liquir. mundata is procured. From Melilotus altissimus 

 and M. officinalis is obtained Herba Meliloti ; from Ononis spinosa, Rad. 

 Ononidis. From the seeds (Calabar beans) of Physostigma venenosum, a 

 climbing plant of Western Africa, is derived the alkaloid Physostigminum. 

 The stems of Andira Araroba, a tree native of Arazil, contain Chrysarobinum 

 in the form of a powdery excretion. The heart-wood of Pterocarpus santalinus, an 

 East Indian tree, yields Red Sandalwood, Lignum Santali rubrum (Pterocarpi 

 Lignum). Toluifera Balsamum, a tree growing in South America, has cortical 

 balsam-canals which yield the Balsam of Tolu, Balsamum tolutanum ; Balsamum 

 peruvianum, the Balsam of Peru, is supplied by Toluifera Pereirae (San Salvador). 



Order 21. Myrtiflorae 



Flowers perigynous or epigynous, usually actinomorphic ; 

 perianth mostly TETRAMEROUS ; andrcecium variable ; gyncecium 

 entirely SYNCARPOUS ; ovary septated ; seeds devoid of albumen. 

 Leaves generally opposite and exstipulate. 



The flowers of the Myrtiflorae are very similar to those of the 

 Bosiflorae. Both orders are characterised by the variability displayed 

 in the structure of their flowers. In both orders the flowers are 

 actinomorphic, perigynous or epigynous, and have a tendency to 

 increase the number of their parts by splitting, particularly in the 

 androecium, which in consequence becomes polyandrous in the majority 

 of the Myrtiflorae, just as in Bosiflorae. The main difference in the 

 structure of the flowers of the two orders is exhibited in the gyncecium, 

 which in the Bosiflorae consists, at least in the stigmatic region, of 



