288 

 Anomalies. Lilsea has no perianthium. 



Essential Character — Sepals and petals both herbaceous, rarely absent. Stamens 6. 

 Ovaries 3 or 6, superior, cohering firmly ; ovules 1 or 2, approximated at their base, erect. 

 Fruit dry, 1- or 2-seeded. Seeds erect ; albumen wanting- ; embryo having- the same direc- 

 tion as the seed, with a lateral cleft for the emission of the plumule.— Herbaceous bog-plants. 

 Leaves ensiform, with parallel veins. Mowers in spikes or racemes, inconspicuous. 



Affinities. The plumula lying within a cleft on one side of the embryo 

 fixes these plants nearer Aroidece than Alismaceae, to which they are sometimes 

 referred, principally on account of their want of albumen ; and the depaupe- 

 rated state of their floral envelopes confirms the relationship. Juncaginerc are 

 most nearly allied to Fluviales, which are readily distinguished by their float- 

 ing habit and pendulous ovules. The genus Scheuchzeria is a transition from 

 Juncaginese to Junceee. 



Geography. Marshy places in most parts of the world may be expected 

 to indicate traces of this order, which is found in Europe, Asia, and North 

 America, the Cape of Good Hope, and equinoctial America. 



Properties. Unknown. Triglochin has a salt taste. 



Examples. Lila^a, Cathanthes, Triglochin, Scheuchzeria. 



CCLX. PISTIACE^E. The Duckweed Tribe. 



Pistiaceje, Rich, in Humb. ct Bonpl. N. G. et Sp. 1. 81. (1815)": Lindl. in Hooker's Fl. Scot. 

 2. 191.(1821); Synops. 251. (1829).— Lemnaceje, Dec. and Duby, 532. (1828.) 



Diagnosis. Floating monocotyledons, with solitary naked spathaceous 

 flowers, and the stem and leaves confounded. 

 Anomalies. 



Essential Character.— Flowers' 2, naked, enclosed in a spatha. Stamens definite. 

 Ovarium 1-celled, with 1 or more erect ovules • style short ; stigma simple. Fruit mem- 

 branous or capsular, not opening, 1- or more seeded. Seeds with a fungous testa, and a 

 thickened indurated foramen; embryo either in the axis of fleshy albumen, and having a late- 

 ral cleft for the emission of the plumule, or at the apex of the nucleus.— Floating plants, with 

 very cellular, lenticular, or lobed stems and leaves confounded. Flowers appearing from the 

 margin of the stems. 



Affinities. These are plants of a still simpler organization than Fluviales, 

 like them apparently destitute of spiral vessels, and not producing any separate 

 stem or leaves, but a body formed out of both, from within the substance of 

 which proceeds a membranous spathe containing one naked staminiferous and 

 one naked pistilliferous flower ; a stem and two flowers thus constituting 

 the whole of the plant. But if an abstraction be made of the simplicity of this 

 structure, and the organization be considered as if it belonged to plants of a 

 more highly developed character, it will be found that these are really nothing 

 but Aroidea, the spadix of which is reduced to two flowers of different sexes. 

 But while the accuracy of this view of the nature of Pistiacere is not likely to 

 be questioned, it must be borne in mind that this very reduction of parts is in- 

 consistent with the notion of Aroidea), properly so called ; and hence the neces- 

 sity of constituting a particular order. I find from an examination of seeds of 

 Pistia, most kindly procured from India for me by Dr. Wallich, that the em- 

 bryo is a minute body lying at the apex of the albumen ; in Lemna it occupies 

 the axis ; in both there is a fungous testa, with a remarkable induration of the 

 foramen of the secundine. The embryo of Pistia is very minute, and perhaps 



