380 DK. A. B. liENDLE — SYSTEMATIC 



in Linna3us's herbarium (written up by himself Najas marina) are all i^. marina var. 

 anyustifolia. In the ' Genera Plantarum ' Najas forms with Zannicliellia and Oyno- 

 morhim the order Monandria of Class XXI., Monoecia; in the ' Species Plantarum' it 

 comprises the order Monandria of Class XXII. , Dioecia. 



In 1785 Allioni (Flora Pedem. ii. 221), ignoring Linnseus's species, united Micheli's 

 first and second under the name N. major, and distinguished the third as N. minor. 

 Schkuhr (Bot. Handb. iii. 252, t. 296 [1808]) w^as the first to recognize the difference 

 between male flowers of the two species. 



In 1801 Willdenow (in Mem. Acad. Roy. Sc. Per. 1798, pt. i. 87) founded the genus 

 Canlinia, in w^hich he included C. flexilis, C^ fragilis ( = K minor), and C. indica. 

 R. Brown, how oyer (Prodromus, 345 [1810]), reunited Caulinia and Najas, at the same 

 time describing a new species, N. tenmfolia. Later Ascherson (Flora Prov. Brandenburg, 

 i. 669 [1864]) divided the genus into two sections : Eunajas, containing N marina, and 

 Caulinia, with N minor and N. flexilis, 



A. Braun in the same year (in Journ. Bot. 1861, 271), in his * Revision of the Genus,' 

 retains Ascherson 's sections. Braun's is the first attempt to deal wdth the whole material 

 under the genus, and is an invaluable contribution to a systematic arrangement of the 

 species, of which he distinguishes eight, with numerous varieties. For specific characters 

 he relies primarily on the form of the leaf-sheath, secondarily on that of the leaf-teeth. 



Magnus in 1870 followed wdth the ' Beitrage z. Kenntniss d. Gattung Najas, ^ to which 

 we have already referred, by far the most important publication on the subject that 

 had hitherto appeared. Of special value w^as his investigation of the flower and fruit, 

 in the structure of which he indicated the important differences on which are based the 

 specific characters adopted in the following arrangement. 



The most important work since 1870 has been that of Magnus himself, who elaborated 

 the genus for Engler & Prantl's ' Pflanzenfamilien ' ; of K. Schumann, who has mono- 

 graphed the Brazilian species in the ' Flora Brasiliensis ' ; of Morong, whose researches on 

 the Xortli -American species appeared in the publications of the Torrey Botanical Club ; and 

 of C. Bailey, who gave a valuable account of N. graminea in the Journal of Botany (1884). 



2. Mo7'phological. 



The j)lants are small herbs growing completely submerged in fresh or brackish water, 

 attached to the soil by fibrous roots springing from the base of the stem or the lower 

 nodes of the branches. 



The main stem branches shortly above tlie base. The branches may be long and 

 spreading, giving a diffuse habit, or ascending from a decumbent base with a grass-like 

 grow^th, or may iorm a much-branched system in which the lateral axes, growing with 

 equal vigour to that of the main axis, entail a regular dichotomous, often bushy habit. 

 Frequently the elongated shoots end in a bushy dichotomous growth. 



The length of the internodes varies widely, according to the general habit. The inter- 

 uodes are usually unarm^ed, but in N. marina and some of its varieties bear short 

 subconical cr triangular teeth ending in a sharp browm spine-cell. 



