49 



XXXVIII. SAXIFRAGEiE. The SAxirnAGE Tuice. 



SAXiFRAOiE, Juss. Gen. 308. (1789); Vent. Tail. 2. 277- (1799) — Saxifraoejf., Dec. 

 and Dubi/,20T. {1828); Lindl. St/nops. 66. (1629.) 



Diagnosis. Polypetalous dicotyledons, with perigynous definite stamens, 

 (2)"ovaria adhering more or less to the calyx and to each other, indefinite 

 seeds, and no stipulse. 



Anomalies. Parnassia has 4 parietal placentae opposite the lobes of 

 the stigma. Petals sometimes absent. Adoxa is a doubtful genus of the order, 

 with a berry of several cells. In Heuchera the flowers are irregular. 



Essential Character Cali/oe either superior or inferior, of 4 or 5 sepals, which 



cohere more or less at their base. Petals 5, or none, inserted between the lobes of the calyx. 

 Stamens 5-10, inserted either into the calyx (perigynous), or beneath the ovarium (hypogy- 

 nous) ; anthers 2-celled, bursting longitudinally. Disk either hypogynous or perigynous, 

 sometimes nearly obsolete, sometimes annular and notched, rarely consisting of 5 scales. 

 Ovarium inferior, or nearly superior, usually consisting of 2 carpella, cohering more or less by 

 their face, but distinct at the apex ; sometimes 2-celled with a central placenta ; sometimes 

 1 -celled with parietal placentae; rarely 4- or 5-celled. Styles none. Stigmata se%%\\e on the 

 tips of the lobes of the ovarium. Fruit generally a membranous 1- or 2-celled capsule with 

 2 bracteae ; rarely a 4-celled 4-valved capsule ; sometimes a 4-ceUed berry. Seeds numerous, 

 very minute ; usually with long hexagonal reticulations on the side of a transparent testa. 

 Embryo taper, in the axis of fleshy albumen, with the radicle next the hilum — Herbaceous 

 plants, often growing in patches. Leaves simple, either divided or entire, alternate, with- 

 out stipulae. Flower-stems simple, often naked. 



Affinities. Most nearly allied to Rosaceee, with the herbaceous part 

 of which they agree in habit, and from which they differ in their polyspermous 

 partially concrete carpella, albuminous seeds, and want of stipulae. From 

 Cunoniacese they are divided rather by their habit, and by the want of sti- 

 pules, than by any thing very positive in their fructification-; the principal 

 characteristic feature of which consists in the more perfect concretion of the 

 carpella. Baueraceae are known by their habit, indefinite stamens,_and pecu- 

 liar dehiscence of the anthers. To Caryophylleae their habit allies them ; but 

 they differ in the insertion of their stamens, their placentation, the situation 

 of their embryo, and otherwise. Portulaceae, which may be compared with 

 them, particularly on account of the situation of their stamens, want of sti- 

 pulae, and albuminous seeds, differ essentially in the structure of the embryo, 

 in the want of symmetry in the parts of the flower, and in placentation. 

 Grossulacece, however different they are in habit, agree very much in the 

 general structure of the flowers ; they differ in the ovarium being com- 

 pletely concrete and inferior, with two parietal placentae, in the seeds 

 being attached to long umbilical cords, in the albumen being corneous, and 

 the embryo extremely minute. Chrysosplenium and Adoxa are both re- 

 markable for the want of petals; and Parnassia, which I think, upon the 

 whole, is a genuine genus of this order, exhibits the singular anomaly of 

 placentae being opposite the lobes of the stigma, an unilocular ovarium, 

 the shell of which consists of two distinct plates connected by an interven- 

 ing loose substance, and a peculiar development of an hypogynous disk, 

 which assumes the form of 5 fringed scales, alternate with the stamens, and 

 of a highly curious structure. Adoxa, which has a berry of several cells, and 

 which is always referred here, appears to me far more anomalous than Par- 

 nassia. Drummondia has the stamens equal in number to the petals and 

 opposite them, thus indicating some analogy with the monopetalous Primu- 

 laceae. 



Geogkai'iiy. Little elegant herbaceous plants, usually with white • 



