'ZW JUNCAGINACE^. [Endogens. 



Order LXVI. JUNCAGINACEjE.— Arrow-grasses. 



JuncagineEe, Rich. Anal. Fr. (1808) ; Mem. Mus. 1. 364. (1815) ; Endl. Gen. p. 127 ; Meisner, p. 364; 

 Ktinth Emm. 3. 141.— Potaraogetonere, Rchh. Fl. Excurs. 1. 6. (1830). 



Diagnosis. — Alismal Endogens xoith scaly floioers, fewseecled simple axile or hasal 

 placcntcB, and an emhnjo slit on one side, with a very large plumide. 

 Herbaceous aquatic or marsh plants, whose leaves have m all cases parallel vems, 

 whether they are narrow and gi'assy, or broad and quite different from the leaf-stalk. 



Flowers , of no conspicuous appearance, white or green, in spikes or 

 racemes. Sepals and petals small and much ahke. Stamens 6 ; anthers 

 usually turned outwards and opening longitudinally. Carpels 3, 4, or 6, 

 free, united or distinct ; o\Tiles 1 or 2, approximated at their base, erect 

 or pendulous. Fruit dry, 1- or 2-seeded. Albumen wanting ; embryo 

 having the same direction as the seed, with a lateral cleft for the emis- 

 sion of the pliunule. 



With the exception of their flowers being § , there is little to separate 

 these plants from the Naiads, in whose Order some of them have been 

 included by all botanists before this time ; for the old distinction of 

 pendulous o\ailes in the Naiads, and erect ones in Arrow-grasses, fails 

 in consequence of Caulinia, and Naias itself, having them erect. The 

 plumule lying within a cleft on one side of the embryo indicates a decided 

 tendency on the part of these plants to Arads, and the incomplete con- 

 dition of their floral envelopes confimis the relationship. The genus 

 Scheuchzeria is a transition from Arrow-grasses to Rushes. 



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. Potamogetons occm* 

 in ditches and swamps as far north as Iceland. 



Triglochin has a salt taste. The root of Potamogeton natans is said 

 to be eaten in Siberia ; the foliage of others is regarded as styptic. 



Triglochin, Linn. 

 Juncago, Tournef. 

 Tristemon, Raf. 



GENERA. 



1 Scheuchzeria, I/jnn. I Peltopsis, Kaf. 



Ruppia, L. _ I Aponogeton, L. 



Potamogeton, L. 



Spathium, Lour. 



Cycnogeton, Endl. 

 I Ouvirandra, Thouars. 

 i Hydrogeton, Pers. 



Numbers. Gen. 7. Sp. 44. 



Position. 



Naiadax;ece. 

 -Juncaginace^. — Ahsmaceae. 

 Juncacece. 



Fig. CXLII.— 1. Leaf of Ouvirandra fenestralis ; 2. a flower cut open ; 3. section of a ripe carpel 

 of O. Bernieriana ; 4, 5. embryo in different positions : the thicker part is the cotyledon, the smaller the 

 plumule. 



Fig. CXLIII.— Triglochin palustre. 1. A flower; 3. a ripe fruit; 4. one ripe carpel opened and 

 exhibiting a seed ; 5. embryo. 



