TYPE 3. GRAINS SIMPLE, CENTRIC, OVAL. 209 



Hydrocharis morstis-rance Linn. (Hydrocharitacew.) Dry embryo. Grains rounded to oval. Length 

 lOfi. Approacliing contric-lcnticular form (tj^pe 2). 



Lachnanthcs tindoria Ell. (Ha-modorncece.) Dry seed. Grains elliptical to lanceolate, frequently 

 slightly curved, sometimes triangular or reniform, usually more or less irregular and toru- 

 lose; one-fifth to almost as broad as long; the broad ones slightly compressed; no lamellae; 

 with frequently a very large cavity with a longitudinal slit. Length 20 to 28ju, breadth 11 fi. 

 It is doubtful whether these grains belong to this tjTDC. 



Naias major Roth.; N. marina Linn. {Naiadacea;.) Dry embryo. Grains oval, three-fifths to four- 

 fifths as broad as long; the broad ones compressed; without lamellse; a loiagitudinal slit from 

 which several fissures usually radiate may be seen from the narrow aspect, and sometimes 

 also from the broad aspect. Length 30/u. 



Zostera marina Linn. (Naiadacea:.) Dry embryo. Grains pressed into true polyhedrons having 

 sharp edges and angles, filling the cells like a parenchyma; one-half to as thick as long; 

 no lamellse; with fissures, which in the isodiametric grains usually radiate from a central 

 cavity and in the oblong ones proceed from a longitudinal slit at right angles to it. 

 Length 30 to 35^. The grains approach centric-spherical (type 1). The grains in the 

 outer parts are of less size, those in the outermost being only 4 to 6/u. They are rounded 

 or oval, and more or less angular. These grains show very distinctly that they belong to 

 the simple type. 



Ruppia maritima Linn. (Naiadacea:.) Dry embryo. Grains rounded to rounded-oval, frequently 

 somewhat angular; wthout lamellse; with a rounded, oblong, or irregular cavity, and 

 usually with irregular radial fissures. Length 25^. Seems closely to approach the centric- 

 spherical type (tjT^e 1). Compound grains of few and usually irregular part-grains are 

 also found (type 15). 



Zajinichellia pedicellata Fries. (Naiadacea.) Dry embryo. Grains rounded to oval; half to as broad 

 as long; the broader ones compressed to about one-half and one-third their width; without 

 lamellse; longitudinal slit marked in the narrow side, also sometimes shows indistinctly in 

 the broad aspect. Length 18/j, breadth 15/:. 



Althenia filiformis Petit. (Naiadacew.) Dry embryo. Grains elliptical to oval, sometimes reni- 

 form; half to as broad as long; the broader ones laterally compressed to about half or more 

 of their width; lamellse indistinct; longitudinal slit is seen in the narrow aspect. Length 

 18;u, breadth 15/u. 



Potamogeton juitaiis Linn. (Naiadacew.) Dry embryo. Grains oval or elliptical; three-fifths to 

 three-fourths as broad as long; the broader ones compressed to about half their width; the 

 narrower slightly compressed; no lamellse; with a longitudinal slit on the narrow side. Length 

 30m, breadth 38^. 



Potamogeton prcelongus. (Naiadacece.) Dry embryo. Grains elliptical or oval; compressed; no 

 lamellse; sometimes with a longitudinal slit on the narrow side. Length 15^, breadth 15/^. 



Calla palustris Lima. (Aroidea:.) Dry seed. Grains spherical or oval, frequently irregular; some- 

 times slightly compressed; half to as thick as long; with a small central cavity, which in the 

 spherical form is ahnost round, in the oval forms oblong. The grains approach the centric- 

 spherical (type 1). 



Anthurium acaide Sweet.; Pathos acaulis Linn. (Aroidece.) Dry seed. Grains spherical or oval, 

 sometimes slightly angular, due to pressure; three-fifths to as broad as long; frequently 

 with a small central cavity. Length 8 to 10m. The grains approach the centric-spherical 

 (type 1). 



Ceratophyllum svbmermm Linn. (Ceratophyllacem.) Dry cotyledons. Grams rounded to oval; two- 

 thirds to as broad as long; slightly compressed; no lamellse; a longitudinal slit is seen on the 

 narrow side, and a delicate one is sometimes visible in the wide aspect; also simple radial 

 fissures. Length 23m, idth 20m. The grains approach the centric-spherical (type 1). 



Nelumbiiim speciosum Willd. (Nymphacece.) Dry cotyledons. Grmns oval or elliptical, sometimes 

 one margin more curved than the others, or even plano-convex, many of them with 3 or 4 

 angles; the -n-ide ones slightly compressed; no lamellse, or single and indistinct; a marked slit 

 is seen on the narrow side, less marked on the broad aspect. Length 20m. The grains de- 

 crease in size toward the smface of the cotyledons, lumule contains oil and starch. The 

 grains small, rounded, somewhat irregular. Size 5 to 6m. (Syn. Nelumho nucifera Gsertn.) 

 14 



