289 



different, and the structure of their Horal organs is essentially unlike. In Hy- 

 drocharidege the ovarium has generally several cells, and each cell contains 

 many seeds, while in Balanophoreae the ovarium is constantly 1 -celled with 

 a single ovuiuni. The former have no albumen; in the latter it is abun- 

 dant. The tribe of Arums, in its habit and characters, has in general a more 

 essential affinity with Balanophorece than Hydrocharidese ; they have both 

 the same arrangement of flowers in spikes, the seeds have in both a fleshy 

 albumen, and the habit of their several genera is much the same. But 

 in Aroideae the ovarium is superior ! He then points out the affinity borne 

 to Cytinus; an affinity about which nothing certain can be said, in the absence 

 of a knowledge of the structure of the seed of the latter. Agardh places these 

 in Urticese, changing the name to Cynomoriese. 



Geography. A small tribe, consisting entirely of leafless plants, para- 

 sitical upon roots, found in the West Indies, South America, some of the 

 South Sea Islands, the Mediterranean, and the Cape of Good Hope. 



PiiorERTiEs, Cynomorium is known for its astringency. Nothing has 

 been stated of the rest. 



Examples. Langsdorffia^ Helosis, Cynomorium, Balanophora, Sarco- 

 phyte or Ichthyosma. 



CCLVIII. FLUVIALES. 



Naiades, Juss. Gen. 18. (1780) in part — Fluviales, Vent. Tabl. 2. 80. (1799).— 



PoTAMOPHiLiE, Rich. Anal. Fr. (1808) PoTAMEiE, Jm.m. Diet. Sc. Nat. 43. 



93. (1826) ; Dec. and Dubij, 439. (1828). _ NAiADEiE, Agardh Aph. 125. (1822). 

 — Fluviales, Rich. Mtm. Mils. 1. 3(;4. (1815) ; Lindl. Si/nops. 2-18. {1829). — 

 Hydrogetones, Link Handb. 1. 282. (1829).— Naiade^e, lb. 1. 820. (1829.) 



Diagnosis. Caulescent floating exalbuminous monocotyledons, with a 

 slit embryo, definite stamens, and dry superior fruit with pendulous seeds. 



Anomalies. Caulinia and some others are said to have no spiral 

 vessels. 



Essential Character. — Flowers hermaphrodite or unisexual. Perianthium of 2 

 or 4 pieces, often deciduous, rarely wanting. Stamens definite, hypogynous. Ovarium 1 

 or more, superior ; stigma simple; ov7ile solitary, pendulous. Fruit dry, not opening, 1- 

 celled, 1-seeded. Seed pendulous; albumen none; embryo antitropous, with a lateral cleft 



for the emission of the plumula Water-plants. Leaves very cellular, with parallel veins. 



Flowers inconspicuous, usually arranged in terminal spikes. 



Affinities. In this order we have the nearest approach, except in 

 Pistiacese, to the division of flowerless plants. The perianthium is reduced 

 to a few imperfect scales, the habit is almost that of Coniferse, and there is 

 in some of the genera either a total absence of spiral vessels, or that form of 

 tissue exists in a very rudimentary state. PoUini asserts, according to De- 

 candolle {Org. Veg. 40), that spiral vessels do exist in them ; but Amici, on 

 the other hand, maintains that there is no trace of them, at least in Caulinia. 

 Ann. des Sc. 2. 42. The manifest affinity of Fluviales to Juncaginese deter- 

 mines a relation on the part of the former to Aroidese, which is confirmed by 

 the tendency to produce a rudimentary spatha in some of them, and by their 

 undoubted resemblance to Pistiacese, which may be understood as reduced 

 Aroideae. It is remarkable that Adanson was aware of this relationship 

 between Aroidese and Fluviales, to which, however, Jussieu, whose Naiades 

 are a very heterogeneous assemblage, did not assent. They are generally 



u 



