584 OX SEEDLINGS 



the plumule by its base. The first two leaves are linear, acu- 

 minate, one-nerved and Grass-like. The ultimate ones are 

 oblong- elliptic and comparatively broad. 



The primary leaves are often, if not always, relatively 

 very narrow, and the ultimate ones in several genera are 

 broad, oblong, elliptic, oval or sagittate. Those of Sagit- 

 taria montevidensis are sometimes eighteen to twenty-four 

 inches wide and proportionately long. 



Alisma Plantago, L. 

 Germination (fig. 684). 



Seeds sown in a greenhouse, in soil sunk in water, germinated 

 in three days. 



The carpels are cuneate, or rather like the segments of an orange, 

 and the seed lies in the interior so that the radicle of the curved 

 embryo occupies the outer and thicker part of the carpel. The 

 radicle being much the thicker part of the embryo requires this 

 accommodation. 



The hypocotyl first emerges, and ends very bluntly or even trun- 

 cately with a thickened margin around the tip (fig. 684, A). 



Three days after germination (fig. 684, B) the thickened margin at 

 the base of the hypocotyl gives out numerous root-hairs which fix the 

 plantlet in the soil. The place from whence the plumule should 

 emerge is dimly visible at the base of the slender cotyledon. The 

 carpel or achene is now suspended at the tip of the cotyledon. 

 Hypocotyl very short. Neither the radicle nor the lateral adventitious 

 roots are yet visible. 



Four days after germination (fig. 684, c) the cotyledon rises .up, 

 freed from the achene, but is still slightly twisted at the end. 



Seven days after germination (fig. 684, D) the cotyledon becomes 

 much elongated, narrowly subulate or filiform, tapering slightly up- 

 wards and straight. The root-hairs are still copious at the base of 

 the short hypocotyl, and the primary root has become considerably 

 elongated. The plumule is also considerably advanced. 



Twelve days after germination (fig. 684, E) the cotyledon has not 

 altered. First leaf linear, acuminate, thin, membranous, showing 

 a distinct midrib. An adventitious rootlet is seen just pushing from 

 the first node, above the hypocotyl. Primary root elongated and 

 furnished with root-hairs nearly to the tip. 



Nineteen days after germination (fig. 684, p) the cotyledon is still 

 unaltered. First and second leaves linear, acuminate, with a distinct 



