XyRiDALEs.l XYRIDALES. 18o 



Alliance XIV. XYRIDALES.— "Y^rb Xyridal Alliance. 



Diagnosis. — Hypogynous bisexual tripetaloid Endogens, tvith copious albumen. 



It is in this Alliance that, among Endogens with a free ovary, the first distinct separa- 

 tion of a corolla from the calyx takes place, in the form of (2 or) 3 petals. Hence the 

 essential character of the Alliance is its tripetaloideous condition. In the absence of 

 that circumstance it is not to be distinguished from Jimcals on the one hand, or LiUals 

 on the other. The Waterworts (Philydracese) seem to have anticipated the tripetaloid- 

 eous organization by forming petals before sepals, and hence they present the anomaly 

 of a flower ^ith a very conspicuous corolla having no calyx, the office of which appears 

 to be performed by spathaceous bracts. X>Tids resemble Sedges with a corolla, and are 

 no doubt akin to Pipeworts (Eriocaulaceee). Spiderworts are analogous to Parids 

 among Dictyogens, and as for the Mayacs they may be compared to Leptanthus among 

 Pontederas, or to Potamogeton among the Arrow-grasses. 



Natural Orders of Xyridals. 



Sepals 0. Petals 2. Stamem 3, of which 2 are abortive. Embryo 1 ^^^ Philydrace^. 



axile, in fleshy albumen , . . . v J ' 



Sepals^. Petals 3. Stamens S fertile. Carpels opposite sepals.! ^^^ ^^,^^^^^^^^ 



PlacentcB paHetal. Embryo minute, on the outside of fleshy albtcmen j 

 Sepals 3. Petals 3. Stamens 6 (or 3). Carpels opposite sepals. ^ 



Placenta axile. Embryo trochlear, half immersed in fleshy Vo6. Commelynacejc. 



oMiumen J 



Sepals 3. Petals 3. Stamens 2> ; {anthers one-celled). Carpels! 



opposite petals. Placentce parietal. Embryo minute, on the v57. Mayace^. 



outside of fleshy albumen ■ .... J 



