364 ON SEEDLINGS 



and the linear-oblong cotyledons broader than its width, these are 

 thrown into various contortions, lying in the broad plane of the seed. 



Acer campestre, L. 



Seeds suborbicular, rather broader on the attached side, much 

 compressed laterally, and conforming to the shape of the cavity of 

 the samara ; seed-coat double ; hilum on the basal edge. 



Embryo large, filling the cavity of the seed ; cotyledons incum- 

 bent, with their backs to the placenta, originating in the narrow 

 plane of the seed ; but as they get too large for the space, becoming 

 twisted round so as to lie in the broad plane with their edges 

 to the placenta ; finally getting too long for the seed, they form two 

 large folds in the middle, and the tips are thrown back over the 

 basal portion close to the radicle, between which and the edges of 

 the basal portions they always lie ; radical inferior, terete, rather 

 pointed, curved at its base, or gradually throughout its length. 



Acer dasycarpum, Ehrh. 



Seed broadly oblong, laterally flattened, conforming to the cavity 

 of the carpel, exalbuminous ; seed-coat double ; testa moderately 

 thick and black ; tegmen thin and membranous. 



Embryo large, filling the seed, yellowish ; radicle terete, occupy- 

 ing the lower side of the seed ; cotyledons incumbent originally, 

 that is with their backs to the placenta, but ultimately turning 

 round with their edges vertical to the axis of the fruit and their 

 tips towards the placenta ; by so doing they place themselves in the 

 broad plane of the laterally compressed seed. After reaching the 

 base of the seed close to the hilum they become folded back again 

 towards the farther end, and in so doing one apical half is folded 

 inside the other. In the specimen examined, the two cotyledons 

 were not strictly opposite, but placed obliquely. There was, 

 however, no plaiting or folding. Radicle filiform, straight, occupy- 

 ing the lower edge of the compressed seed. Petioles of the 

 cotyledons slightly curved. 



Acer circinatum, Pursh. 



Seed oblong, obtuse at either end, tumid, conforming to the 

 cavity of the ovary ; seed- coat double ; hilum at one end of the seed ; 

 raphe encircling the whole basal portion of the seed ; funicle' short, 

 thick, and with a development of cortical tissue. 



Embryo originating in the neck-like portion of the ovule, which 

 is curved round against a cortical development of tissue from the 

 funicle ; radicle terete and stout, equal to the neck of the ovule 



