FicoiDALEs.] FICOIDALES. 523 



Alliance XL. FICOIDALES. — The Ficoidal Allianx'e. 



Diagnosis. — Perigynous Exogens, tuitJi monodichlamydeous jiowers, central or axile 

 placentce, a polypetaloics corolla, if one is present, and an external embryo curved 

 round a small quaiitity of mealy albumen. 



These plants are for the most part fleshy-leaved herbs or bushes, bearing very great 

 resemblance, m some cases, to Purslanes m the Silenal Alliance, and like those plants, 

 having for theu' character a central placentation combined with an annular embryo 

 and mealy albumen. They are, in fact, the perigynous form of Silenals, and must be 

 regarded as standing on the frontier of that AUiance. Like Silenals, the Ficoidals 

 comprehend plants both \\dth a high development of the corolla, and without a trace 

 of it. They approach the Epigynous structm'e in some respects ; but although their 

 carpels are partially adlierent with the calyx in a large proportion of the Alliance, 

 yet the styles are almost always distinct, and generally the carpels also in some degree. 

 Torch-thistles are no doubt a kindred race, but the exigencies of a lineal arrangement 

 compel the systematist to separate them by a long interval. 



The great marks of the Ficoidal Alliance are the perig^mous stamens, curved 

 external embryo, and mealy albumen. It may be presumed that its axile placen- 

 tation is a mere modification of the central, and not derived from the margins of 

 carpellary leaves ; but this is a point which cannot be always decided. 



Natural Orders op Ficoidals. 



Petals absent. Sepals distinct. Fruit inclosed in a membranous l,^f. Basellacee 

 or succulent calyx. Carpel single, solitary. Seed erect ... J * 



Petals numerous,, conspicuous. Carpels several, consolidated . . 200. Mesembryace^. 



Petals absent. Carpels several, consolidated 201. Tetragomace^. 



Petals absent. Sepals united into a tube. Carpel single, solitary. \ ^^2 Scleranthace.e 

 Fruit inclosed in the hardened calyx tube J 



