56 MR. J. MIERS ON THE FAMILY OF TRIURIACEjE. 



the plants of this family differ wholly from the Triuriacece, in having distinct, entire, 

 large leaves, with long amplexicaul petioles, and intrapetiolar vaginant stipules, in their 

 female flowers arising from the superior axils, in the frequent absence of any perianthium, 

 ovules often suspended from the ventral suture, and very delicate membranaceous testa. 

 Their exalbuminous macropodous embryo may be considered as an approximation to the 

 structure of the nucleus of Sciaphila. 



With the Juncaginece they agree in their inconspicuous spicate flowers, numerous 

 carpels, with a solitary erect ovule and exalbuminous seeds ; but these again differ in their 

 large leaves, with parallel nervures, 2-serial floral envelope, extrorse stamens upon long 

 filaments, and sometimes two ovules in each carpel. The Juncaginece, however, have been 

 considered by some as a suborder of the Alismacece, by others to be more nearly allied to 

 Fluviales and Aroidece, on account of their spicate flowers : indeed, though placed at so 

 great a distance in the system by Endlicher, they are really so closely allied, that the 

 genera Ruppia and Potamogeton are placed by some botanists in Fluviales and by others 

 in Juncaginece. 



If we agree in placing these four families in closer juxtaposition in the system*, the 

 Trvuriacece will find a place near them; but, upon the whole, the greatest amount of 

 approximative characters will be seen to lean towards the Fluviales, especially through 

 Potamogeton (which genus is arranged by Mr. Brown among the Alismacece), and which 

 possesses a simple perianth of four segments in a single series, with valvate aestivation, 

 and four stamens opposite to them, globose simple pollen and uniovular carpels ; and 

 although it bears hermaphrodite flowers, it must be remembered that Sciaphila is some- 

 times bisexual. Najas and Caulinia, as before observed, present also carpels with a soli- 

 tary erect ovule. 



It now only remains to define the characters of this small order. 



Tritjriace^;, Miers (1841). Triuracece, Gardn. (1843). Triuridacece, Lindl. (1846). 



Herbm parvulae, subhyalinae ; rhizomate fibroso, interdum substolonifero ; caule subsimplici, textura cellu- 

 losa, vasis deferentibus in axi centralibus ; foliis alternis, bracteiformibus, sessilibus, nervis destitutis. 

 Flores monoici, vel dioici, rarius polygami, spicati ; pedicellis alternis, 1-floris, basi bracteatis. 

 Perianthium in utroque sexu simile, 3^1-6-8-partitum, hyalinum, textura celluloso-bullata, vel 

 papilloso-rugosa ; laciniis ovatis, acutis, basi in tubum brevissimum coalitis, apice interdum processu 

 elongato donatis, aestivatione valvatis. Stamina numero varia, pauca, in fundo perianthii fere sessilia, 

 supra androphorum saepissime magnum carnosum inserta; anthera 4-loculares, 2-valves, rarius in 

 lobos 2 sejunctae. Ovaria plurima, in gynaecium toro adnatum densissime aggregata, 1-locularia ; 

 ovulo unico, e basi erecto. Stylus excentricus, introrsum lateralis, saepissime fere basilaris, glaber 

 aut plumoso-fimbriatus. Stigma obsoletum, vel truncato-clavatum. Carpidia plurima, baccata, 

 radiatim excentrica, obovata, stylo persistente fere basilari notata, coriacea et indehiscentia, vel 

 interdum utricularia dorso valvatim dehiscentia ; caryopside obovata, tela arillaeformi donata : testd 



* This we find adopted in the ' Prodromus Floras Novee Hollandise ' of Mr. Robert Brown, where the Aroidece, 

 Fluviales, Alismacece, and Juncaginece are placed in contiguity, with the intervention of Pandanus alone, of which it 

 is worthy of remark that it also offers the peculiarity of an entire and simple embryo : and nearly the same arrange- 

 ment occurs in the system of De Jussieu. 



