8 



OX SEEDLINGS 



lCffl. 



FIG. 394. 



Echinocactus 



viridescem. 



Nat. size. 



Echinocactus viridescens, Nutt. (fig. 394). 

 Primary root short, tapering, with a few fleshy lateral rootlets, 

 and abundance of root-hairs. 



Hypocotyl succulent, short, erect, but distinctly 

 thinner than the stem, pale transparent green, suf- 

 fused with purple, and mottled with pale markings, 

 4-5 mm. long, 6 mm. thick. 



Cotyledons reduced to minute, scarcely elevated 

 green teeth. 



Stem succulent, erect, oblong or globose in the 

 seedling stage, glabrous, shining, coloured like the 

 hypocotyl, slightly five- or six-angled and furnished 

 with tufts of spines in as many rows ; spines unequal 

 with usually the central one much longer, red or 

 pink when young, ultimately white, pubescent and 

 seated on the top of little elevations of the stem in 

 a cushion of short cottony or woolly hairs. 

 Leaves none. 



The seedling of Echinocactus Orcuttii, Engelm., closely re- 

 sembles that of the last species. 



Cereus Napoleonis, Hook. (fig. 395). 



Fruit baccate, scaly, one-celled, many-seeded ; pericarp pulpy. 

 Seed irregularly suborbicular, and angled, compressed, glabrous, 

 black, minutely tuberculated all over, but 

 most conspicuously along about half its margin 

 which is bordered with a ring of thickened 

 tissue ; testa much thickened, crustaceous or 

 almost bony ; tegmen much thinner, mem- 

 branous, pale-coloured, finely reticulated ; 

 hilum very large and conspicuous, forming a 

 deep bordered pit at the base of the seed; 

 micropyle contiguous, inconspicuous, and ap- 

 pearing lateral owing to the size of the hilum. 

 Endosperm wanting. 



Embryo bent or hooked, or hammer-like, 

 occupying the whole interior of the seed, 

 fleshy, colourless; cotyledons short, oblong, 

 obtuse, entire, semiterete, fleshy, placed with 

 their edges to the compressed sides of the seeds and consequently 

 in the narrow way of the latter, bent at right angles to the radicle ; 

 radicle about as long as the cotyledons, oblong, suddenly tapered 



FIG. 395. 



Cereus Napoleonis. 

 Longitudinal section of 

 seed, x9: h, hilom; 

 m, micropyle ; oc, 

 testa ; ic, tegmen ; 

 c, cotyledon. 



