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MK. A. W. BENXETT ON THE GEXUS HYDROLEA. 2G7 



times glabrous, more often clothed with a viscid glandular pu- 

 bescence, sometimes, in the genus Wi^andia, with acrid stinging 

 glands; other species are armed with sharp spines. The branches 

 and leaves are alternate, the latter always simple, entire or 

 serrated, generally stalked, and exstipulate. The flowers are 

 hermaphrodite, sympetalous, regular, generally blue, sometimes 

 very handsome, often arranged in corymbs, or scorj)ioid cymes. 

 They are mostly inhabitants of dry places, some species, however, 

 of marshes and the margins of rivers, especially the Ilydrolece ; 

 and, as Choisy remarks, this genus is the only one in the order 

 which is distributed over both hemispheres. The best descrip- 

 tions are to be found in Choisy's ' Synopsis ' in the tenth 

 rolume of DeCandolle's ' Prodromus,' and in his more extended 

 ^ Description des Hydroleacees,' from the Memoirs of the 

 Soc. Phys. et d' Hist. Nat. of Geneva, contained in the ' Annales 



des Sciences Naturelles,' 1st series, vol. xxx. and 2nd series, 

 vol. i. 



The genus HyJrolea is distinguished from all the other genera 

 of the order, except Petit-Thouars's very unsatisfactory Mada- 

 gascan SydroUa^ by the bilocular capsule dehiscing septicidully, 

 the single dissepiment bearing in the middle two fleshy fungus- 

 like placentae, and is therefore practically coextensive witli the 

 suborder Hydrolese. The species are herbaceous or subfruticose, 

 glandular-pilose or glabrous; sometimes armed with axillaiy 

 spines ; the leaves alternate and entire ; the flowers blue, often 



very conspicuous, axillary or corymbose, yielding a yellow fra- 

 grant oil. 



Linna?us knew only one species of Hydrolea (besides two 

 others described under other genera) ; Choisy, in his ' De- 

 scription des Hydroleacees,' makes eight, and in DeCandolle's 

 * Prodromus' eleven. A careful examination of the specimens 

 preserved in the Herbaria at Kew and the British Museum, and 

 of the American species in those of Berlin, Munich, and Vienna, 

 induces me to increase this number to thirteen, by the suppres- 

 sion of two doubtful species, and the addition of one already 

 described by Grisebach, and of three new species, two of which are 

 from Tropical Africa, and one from Brazil. 



The authorities for the genus are as follows : — viz. Hydrolea^ 

 I^inn. Gen. 318; Gartner, vol. i. p. 263, t. 55 \ Aubl. Guian. 

 t- 110 ; Cavanilh Ic. t. 529 ; Bot. Eeg. t. 506 ; Kunth in Ilumb. 

 et Bonpl. Nov. Gen. et Sp. vol. iii. p. 125 ; Wight, Ind. Bot. 



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