'^^^6 The Ottawa Naturalist. [Feb. 



tion to be compared with the one so frequently observed in the 

 Dicotyledones. One of the most striking peculiarities noticeable 

 inUhe seedlings of the Dicotyledones is the remarkable contrast 

 between the shape of the cotyledons, especially the epigeic, 

 and the final leaves, and it seems almost impossible to bring these 

 into actual correlation. The diversity of form in the cotyledons 

 is quite considerable, even if their shape be usually much simpler 

 than that of the ultimate leaves, a simplification which may have 

 been produced by arrest, rather than being an indication of 

 leaf-forms that characterized the species in by-gone years, as 

 suggested by some authors. Considered by themselves the 

 epigeic cotyledons represent a multitude of forms, of which the 

 following may be enumerated: "Unear" in Clayionia megar- 

 rhiza 'Parry ,' Menispermum Canadense L., Negundo aceroides 

 Moench, Acer saccharinum Wang; "narrow lanceolate" in 

 Platanus occidenialis L.; "ovate" in Viiis^ riparia Michx., V. 

 (Bsiivalis Michx., Ampelopsis quinquefolia Michx., Clitoria 

 Mariana L. ; "obovate" in Rhns copallina L.; "obovate with 

 auriculate base" in Carpinus Caroliniana Walt.; "oblong" in 

 Cornus florida L., Celaslrus scandens L., Liquidamhar Siyraciflua 

 L. ; " elliptic ' ' in Diospyros Virginiana L. , Liriodendron Tidipijera 

 L.! Sanictda Marylandica L., Thaspium barbinode Nutt.; 

 "spathulate" in Ambrosia irifida L.; "oval" in /sJ/x^.-f Toxi- 

 codendron L.; "reniform" in Hedeoma pulegioides Vers., 

 Geranium maculaium L.; "rotund" in Cassia chamcecrista L. ; 

 "bifid" with diverging broad globes in Ipomcea leptophylla Torr., 

 1 hederacea Jacq.; "bifid" with diverging linear lobes in 

 EschschoUzta 'Californica Cham.; "palmately five-lobed" in 

 Tilia Americana L. . and finally ' ' bipartite with diverging rounded 

 lobes", making the leaf almost obcordate as in Catalpa bignoni- 

 oides Walt. (Fig. 23) ; in Aralia spinosa L. (Fig. 26) the cotyledons 

 are very unequal, the one being obovate, and entire, the other 

 ovate vvith the margins serrate, thus imitating the outline of the 

 leaflets of the mature tree; such distinction in structure _ is, 

 otherwise, very seldom met with, while some modification in size, 

 but not in outline, has been observed in cotyledons of several 

 herbs. We have, thus, in the epigeic cotyledons a number of 

 leaf-types which correspond with those of mature plants, herbs 

 and trees, with the only exception, so far as I know, of the de- 

 compound. If we, on' the other hand, examine the hypogeic 

 cotyledons we notice in these hardly any variation worth speaking 

 of, since these mostly remain enclosed by the seed; they are 

 usually fleshy, entire .' and vary only in length and width, from 

 linear to oblong, etc. 



To classify the dicotyledonous seedlings is a most difficult 

 task, difficult to the same extent as it is to classify the mature 



