ANATOMY OF MEGALODONTA BECKII 337 



fieyag, fieyaXog (megas, megalos) great, large and o^ovg, oSovTog, 

 (odous, odontos) tooth. 



The plants used for study were found submerged in both 

 Bankson and North Bankson Lakes in bloom during the latter 

 part of August and the early part of September. The submerged 

 leaves are opposite or whorled in 3's, and finely repeatedly dis- 

 sected on the palmate plan. The emersed leaves two or three 

 pairs in number are narrowly lanceolate to oblong and laciniately 

 toothed, pinnate and reticulately veined. The lower emersed or 

 intermediate leaves are often more or less deeply lobed or cleft 

 appearing as transition forms from the aquatic to the aerial forms. 

 The 'aquatic foliage invariably withers when by design or accident 

 exposed even for a short time to the air though the emersed 

 may for a rather long time remain undecayed when submerged. 

 The plant grows in rather deep water from several decimeters 

 to several meters, the lower stem or rhizome rooting below the 

 mud level. The submerged floating stem and the aerial part are 

 rather similar in structure and have large air cavities in the cortical 

 region as also in single large central air space in the pith. The 

 rihzome rooting below in the mud is devoid of this central air 

 space and the cortical spaces are smaller and fewer. The adven- 

 titious roots at the nodes, even on the floating stem, and the 

 upper roots are conspicuously green with chlorophyll. These roots 

 reach down several decimeters or over a meter and when reaching 

 the muddy bottom branch into numerous smaller divisions. The 

 part of the stem creeping in the mud is not much over half the 

 diameter of the floating aquatic stem, or about 2 mm. and some- 

 times less. The aquatic foliage is nearly as persistent as that of 

 Cabomba but not as deciduous as that of Neobeckia. (Roripa or 

 Nasturtmm aquatiiim). A rather poor drawing of the plant is 

 found in Torrey's Flora of New York already cited and one some- 

 what better perhaps in Britton and Brown's Flora, both editions 

 pp. 440 and 500 respectively. The characters of the plant may be 

 had in the works cited as also from our common manuals more 

 or less incompletely. 



THE ROOT. 



The young root has a well marked stele surrounded with well 

 defined endodermis limiting the periblem (Fig. i).- The cell structure 

 of the epiblema seems in no particular way different from that of the 



