BOTANY. . 17r) 



a two-valved sarcocarp. Rutese are found chiefly in the soutliern part (4' 

 the temperate zone, as in the south of Europe, while Diosmefe abound at the 

 Cape of Good Hope and in New Holland. The recently discovered 

 Rutosma texensis is the sole representative of the Rutefe in America. 

 Lindley mentions 48 genera and 400 species. Examples : Ruta, Dictamnus. 

 Diosma, Barosma, Correa, Boron ia, -Rutosma. 



Dictamnus albus (j?Z. 68, ßg. 10); a, ^, a flower branch and leaf; c, 

 stamen ; 6?, pistil ; <?, burst capsule ; /", half of the capsule with the endocarp 

 separated ; ^, endocarp with the seed ; A, a seed. 



Order 167. Zygophyllace^, the Guaiacum Family. Calyx four- or five- 

 parted, with convolute aestivation. Petals alternate with the calycine 

 segments, with imbricated aestivation. Stamens twice as many as the 

 petals; filaments dilated at the base, usually arising from scales. Ovary 

 simple, four- or five-celled ; divisions occasionally formed by spurious 

 dissepiments. Ovules two or more in each cell, usually pendulous ; style 

 simple, four- or five-furrowed ; stigma simple, or four- or five-lobed. Fruit 

 capsular, or rarely fleshy, with four or five angles or wings, four- or five- 

 valved, either opening by loculicidal dehiscence, or indehiscent. Seeds 

 few, usually with whitish albumen, sometimes exalbuminous ; embryo green, 

 with foliaceous cotyledons, and a superior radicle. Herbs, shrubs, or trees, 

 with opposite, stipulate, usually compound leaves, which are not dotted, and 

 hermaphrodite flowers. Tliey occur in various parts of the world, chiefly 

 in warm extratropical regions, as in the south of Europe, America, Africa, 

 and India. The order has been divided into two sections ; 1. Zygophyllea^. 

 having albuminous seeds. 2. Tribulese, having exalbuminous seeds. 

 Lindley mentions seven genera, comprising one liundred species. Examples : 

 Zygophyllum, Guaiacum, Tribulus, *Kallstra3ma. The order is represented 

 in North America by Kallstroema maxima alone. Jussieu includes the last 

 four orders as sub-orders, under one general order, Zj^gophyllacese. The 

 wood of Guaiacum ofiicinale, a West Indian tree, is known as lignum vita^. 

 This species yields a resinous matter, known as Gum guaiac. 



Guaiacum ofiicinale (pi. 68, ßg. 9) ; a. flowering branch ; 5, anthers ; c, 

 pistil ; 6?, an ovule magnified ; e, fruit. 



Order 168. Brexiace^, the Brexia Family. Calyx small, persistent, of 

 five coherent sepals, with an imbricated aestivation. Petals five, with 

 twisted aestivation. Stamens five, alternate with the petals, arising from a 

 narrow cup or disk, which is toothed between each stamen; anthers 

 bilocular, erect, opening longitudinally and introrsely. Ovary five-celled : 

 ovules numerous, in two rows ; placentas central ; style one ; stigma simj»le. 

 Fruit drupaceous, five-celled, many-seeded. Seeds having two distinct 

 coverings, anatropal ; embryo straight; radicle cylindrical; cotyledons 

 ovate, obtuse. Trees with coriaceous, alternate leaves, having small 

 deciduous stipules. They exist principally in Madagascar. Lindley 

 associates some perigynous genera with Brexia, and ])]aces the order near 

 Saxifragaceae. He enumerates four genera, including six species. 

 Example : Brexia. 



Order 169. PrrrospoRACE^:, the Pittosporum Family. Sepals four or five, 



175 



