306 SYSTEMATIC BOTANY. 



Plumbaginaceae in habit. Baillon points out an affinity to Celastraceaa. 

 The species are found in India, Asia Minor, and North Africa. The most 

 important is Salvadora persica, supposed to be the Mustard-tree of the 

 Bible, its fleshy fruit having an aromatic odour and tasting like garden- 

 cress. The bark of its root is used in India as a vesicatory. The leaves 

 of S. indica are purgative. 



LOGAJNTACE.E. 



Coh. Gentianales, Benth. et Hook. 



Diagnosis. Trees, shrubs, or herbs with opposite leaves and interposed 

 stipules sometimes reduced to an elevated line or a ridge ; calyx 4-5- 

 cleft; corolla hypogynous, gamopetalous, regular, 4-, 5-, or 10- cleft, val- 

 vate or contorted or imbricated in aestivation ; stamens springing from the 

 corolla ; ovary superior, usually 2-celled ; style divided above into as 

 many lobes as the cells of the ovary ; ovules numerous or solitary ; fruit 

 capsular, 2-celled, with the placentas finally detached, drupaceous, with 

 1- or 2-seeded stones, or baccate with the seeds immersed in pulp ; seeds 

 with a straight embryo in fleshy or cartilaginous perisperm, sometimes 

 winged, mostly peltate ; embryo straight, radicle inferior. 



ILLUSTRATIVE GENERA. 



Tribe 1. GELSENIE-ZE. Corolla-lobes imbricate ; style bifid; stigmas lateral ; 



fruit capsular. Gelsenium, Juss. 

 Tribe 2. EU-LOGANIE^;. Style simple; stigma terminal ; ovules numerous 



in each cell of the ovary. Spigelia, L. ; Buddleia, L. $ Desfontainea, 



Ruiz et P. ; Usteria, Wittd. ; Strychnos, L. 

 Tribe 3. GJERTNEREJE. Style bifid; cells of ovary I-ovulate; corolla-lobes 



valvate. Geertnera, L. 



Affinities, &c. This Order was formerly associated with Apocynaceas and 

 the neighbouring Orders ; but, as remarked by Bentham, it consists, on the 

 whole, of Rubiaceae with a free ovary, at the same time approaching, by 

 ceitain of its diverse forms, some of the genera of several of the Corollifloral 

 Orders even more nearly than the general mass approach Rubiaceae. To 

 Apocynaceae, which are very near in general structure, some genera, such as 

 Geniostoma, which has contorted aestivation of the corolla, and Mitrasacme, 

 where the carpels are partially distinct below and united above, approach 

 very closely ; Mitrasacme and Mitreola were formerly arranged as doubtful 

 Gentianaceee, and Fagrcea and Potalia approach still more nearly, the 

 former greatly resembling Lisianthus in character, while Buddleia and its 

 allies have been referred to Scrophulariaceae until lately, but are brought 

 into this Order by Bentham, since they cannot be separated from Logania. 

 The main difference from Apocynaceas lies in the stipules ; but these are 

 sometimes reduced to a mere line connecting the leaves : the peculiar 

 stigma of that Order affords another means of separating them ; and the 

 Apocynacpfe often have hypogynous glands, which the Loganiaceae have 

 not. Fr( m Gentianaceae the distinction lies generally in the stipules and 

 the axile placentation ; occasionally the succulent condition of the fruit 

 is required as a decisive mark. From the Scrophulariacese the stipules, 



