532 



BOTANY 



The Gruinales are distinguished from the Columniferae by the 

 partially monadelphous stamens, and by the absence of splitting in the 

 andrcecium. In both orders one whorl of stamens is often suppressed 

 or replaced by staminodia. The absence of a disc and the position of 

 the micropyle distinguish the Gruinales from the allied order Tere- 

 binthinae and the Aesculinae. 



Family Geraniaceae. — Flowers actinomorphic, rarely zygomorphic, 

 pentamerous throughout ; stamens five or ten ; ovary with two ovules 



in each loculus ; carpels prolonged into 

 an awn, and becoming detached, 



WHEN RIPE, FROM A PERSISTENT CEN- 

 TRAL COLUMN (Fig. 501). 



The Geraniaceae are herbs, or, in 

 warm climates, small shrubs, with simple 

 leaves and usually with glandular hairs, 

 which secrete an aromatic oil. The 

 flowers are either axillary and solitary 

 or clustered in inflorescences of various 

 types, and have usually a carmine or 

 crimson corolla. The carpels in many 

 species remain closed, and are forced into 

 the ground by the movements of the 

 spirally- twisting hygroscopic awn (e.g. 

 Erodium). In most of the large-flowered 

 species of Geranium the awns, in coiling, 

 contract with such suddenness that the 

 seeds are shot out from the carpels, which rupture along the ventral 

 suture. The two genera may readily be distinguished, as Erodium 

 (Storksbill) has only five stamens, while in Geranium (Cranesbill) ten 

 are present. 



Geographical Distribution. — Members of tliis family are found widely 

 scattered over all zones. The various species of Pelargonium (flowers zygomorphic), 

 which are so largely cultivated, are indigenous to South Africa. 



The Tropaeolaceae, a small South American family, occupy a systematic 

 position not widely removed from the Geraniaceae. They have zygomorphic 

 flowers, with eight stamens and three carpels. Various species of Tropaeolum, 

 Indian Cress or so-called Garden Nasturtium, are frequently cultivated. 



Family Oxalidaeeae. — Flowers actinomorphic, with ten fertile 

 stamens ; ovary with several ovules in each loculus ; fruit a 

 capsule. Herbs and wood}'- plants with compound leaves ; more 

 rarely with phyllodia. 



A chiefly tropical family, of which Oxalis acetosella, the common Wood-Sorrel, 

 is a familiar representative ; its sour taste is due to the presence of acid potassium 

 oxalate. 



Fig. 501. — Fruit of Pelargonium inqui- 

 nam, x 3. (After Baillon.) 



Family Linaeeae. — Flowers actinomorphic ; four- or five-merous ; 



