560 ON SEEDLINGS 



lanceolate In outline, and only slightly sheathes the plumule 

 with its edges at the base. The plumule is large and excep- 

 tionally well developed, including eight to ten young foliage 

 leaves, of which the outer ones sometimes reach to the apex 

 of the cotyledon. The fleshy conical hypocotyl is about a 

 quarter the length of the cotyledon, and there is no trace of 

 any radicle. 



In Halophila and Thalassia, which inhabit the sea, the 

 embryo consists of a strongly developed lower hypocotyledo- 

 nary, or hypocotyledonary and radicular portion bearing a 

 very distinct but much smaller cotyledon which sheathes the 

 plumule. In Halophila 1 the lower part consists entirely of 

 hypocotyl, the radicle being absent as in Stratiotes. In 

 Thalassia Hemprichii we find according to Solms 2 an ' extra- 

 ordinarily large stem and root portion ' filling the whole under 

 part of the seed, in the apex of which is the small cotyledon 

 and strongly developed plumule. Embryos such as these are 

 termed macropodous (large-footed). 



Stratiotes abides, 3 L. 



Fruit a capsule, six-celled, unequally angled, mucous. 



Seeds anatropous, in the angle of the thick outer and the thin 

 inner wall, almost erect ; raphe towards the centre of the fruit ; 

 niicropyle and hilum contiguous and directed towards the outside 

 wall. Bather long, slightly verrucose, and with a slight carina ; 

 testa hard ; tegmen very thin. 



Endosperm absent. 



Embryo unusually far developed, including eight to ten young 

 foliage-leaves spirally arranged, forming the plumule; cotyledon linear- 

 lanceolate, thick, fleshy, only very slightly embracing the plumule 

 with its edges at the base, its apex rounded or pointed and the outer 

 leaves of the plumule sometimes reaching the apex, sometimes 

 shorter; in its axil and also in that of the outer foliage-leaves 

 are two small scales (squamulae intra-axillares) ; hypocotyl fleshy 

 and conical, about one-fourth the length of the cotyledon and bear- 

 ing at the end a particle of dead tissue, the remains of the suspen- 

 sor ; radicle absent. A longitudinal section of the hypocotyl shows 



1 J. B. Balfour, Trans. Bot. Soc. Edinburgh, xiii. (1879). 

 * Solms-Laubach, in Schweinfurth, Flora Aeth. p. 195. 

 Cf. Klinsmann, Bot. Zeit. I860, p. 81, taf. ii. ; and Irmisch, Flora, 1865, 

 p. 81, t. 1. 



