741 



LOASACE.K. 



[Epigynous Kxogkns. 



Order CCLXXXV. LOASACE.E.— Loasaos. 



Loasesp, Juss. Ann. Mus. 5. 18. (1804) ; Diet. Sc. Nat. 27. 93. (1823) ; Knnth in Nov. Gen. el Sp. G. 

 115. (18231 ; DC. Prodr. 3. 339. (1828) ; Endl. Gen. excix. ; Meisner, p. 125.— Gronovieae, Emll. 

 Gen. p. 940. 



Diagnosis. — Cactal Exogens, with distinct sepals and petals, scattered stamens, confluent 

 pendulous ovules, and albuminous seeds. 



Herbaceous plants, hispid, with pungent hairs secreting an acrid juice. Leaves 

 opposite or alternate, without stipules, usually more or less divided. Peduncles axillary, 



1 -flowered. Calyx adherent, 4- 5-parted, 

 persistent, imbricated, and spreading in 

 sestivation. Petals 5 or 10, in two rows, 

 often hooded, with an inflexed, valvate, or 

 contorted aestivation ; the interior often, 

 when present, much smaller than the 

 outer, and truncate at the apex. Stamens 

 00, in several rows, arising from within 

 the petals, either distinct or adhering in 

 bundles before each petal, within the 

 cavity ol which they he in aestivation ; 

 filaments subulate, unequal, the outer 

 ones frequently destitute of anthers. 

 Ovary inferior, 1-celled, with several 

 parietal placentae, or one only in the 

 centre ; style single ; stigma 1, or several. 

 Ovules anatropal, pendulous, rarely 1. 

 Fruit capsular or succulent, inferior, 1- 

 celled, with parietal placentae originating 

 at the sutures. Seeds without aril ; em- 

 bryo lying in the axis of fleshy albumen, 

 with the radicle pointing to the hilum, 

 and flat small cotyledons. 



The relationship of this Order seems 

 to be almost equally divided between 

 Indian Figs and Onagrads, and hence it 

 must stand on the limits of the Myrtal 

 and Cactal Alliances. From the former, 

 however, it differs most, in consequence of its parietal placentation and 1-celled ovary. 

 It is through Pereskia that it passes into Indian Figs, for that genus, if it were to 

 lose its succulence, would almost belong to Loasads ; the species of Rhipsalis too, in 

 which there is a clear distinction between the calyx and corolla, offer another easy 

 transition from Indian Figs to this Order, by way of Bartonia. But while such may 

 be regarded as the most immediate affinity of Loasads, there are others so little remote 

 as to show that among the Epigynous class we have distinct traces of a near parallelism 

 with both the hypogynous and diclinous sub-classes. The first is indicated by the 

 similarity in habit of Blumcnbachia, &c, to Passionflowers, in connection with the 

 great tendency which such genera exhibit to convert their stamens into petaloid pro- 

 cesses ; and, as Endlicher remarks, there is also a plain approach to Turnerads and 

 Crownworts, two other Orders of the Violal Alliance. The relation to diclinous 

 Endogens consists in the resemblance between Loasads and Cucurbits ; a similarity so 

 great, that little serves to distinguish them, except the diclinous flowers and short 

 sinuous anthers of the latter ; in fact, the genus Sphcnantha, referred to Cucurbits, is 

 probably a Loasad if it belongs to either the one Order or the other. Gymnotheca is 

 a very anomalous plant, with neither calyx nor corolla ; Decaisne refers it to Sauru- 

 rads, p. 251. 



All the species are American, and chiefly from the more temperate regions, or tin 

 tropics, of either hemisphere. 



l"ig. CCCCXCVII.- 



vessel ; 4. seeds. 



Fig. CCCCXCVII. 



-Bartonia albicaulis. 1. a flower; 2. ring of stamens; 3. cross section of seed- 



