744 



LOASACE^. 



[Epigynous Exogens. 



Order CCLXXXV. LOASACEiE.— Loasads. 



Loaseae, Juss. Ann. Mus. 5. 18. (1804) ; Diet. Sc. Nat. 27. 93. (1823) ; Kiinth in Nov. Gen. et Sp. 6. 

 115. (1823) ; DC. Prod?'. 3. 339. (1828) ; Endl. Gen. cxcix. ; Meisner, p. 125.— G^ono^1eae, Endl. 

 Gen. p. 940. 



Diagnosis. — Cactal Exogem, ivith distinct sepals and petals, scattered stamens, confluent 



ovules, and albuminous 



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

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



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

 persistent, imbricated, and spreading in 

 aestivation. Petals 5 or 10, in two rows, 

 often hooded, mth an inflexed, valvate, or 

 contorted sestivation ; the interior often, 

 when present, much smaller than the 

 outer, and ti'uncate at the apex. Stamens 

 00, in several rows, arising from within 

 the petals, either distinct or adhermg in 

 bundles before each petal, within the 

 cavity of which they lie 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 sutm'es. 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 mdicated by the 

 similarity m habit of Blumenbachia, &c., to Passionflowers, in connection with the 

 great tendency which such genera exliibit to convert their stamens mto petaloid pro- 

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

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

 Endogens consists in the resemblance between Loasads and Cucm-bits ; a similarity so 

 great, that Httle serves to distmguish them, except the diclmous flowers and short 

 sinuous anthers of the latter ; m fact, the genus Sphenantha, refeiTed to Cucm'bits, is 

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

 tropics, of either hemisphere. 



Fig. CCCCXCVII. 



Fig. CCCCXCVII,— Bai-tonia albicaulis. 1. a flower: 2. ring of stamens; 3. cross section of 

 vessel ; 4. seeds. 



