POLYGON ACE,*: 



441 



papillose, pale green closely striated with red lines ; 1st internode 

 6-9 mm. long. 



Leaves simple, cauline, alternate, stipulate, petiolate, five-nerved 

 at the base and alternately nerved upwards, with branching anasto- 

 mosing veins, deep glaucous-green above, paler and glaucous beneath, 

 glabrous ; petioles semiterete, channelled on the upper side, tapering 

 upwards from a stout base, pale green, pubescent or papillose at the 

 margins on the upper side, shining ; stipules connate by their edges 

 and forming a sheath around the stem to which their bases are 

 adnate, thin and membranous for the greater part, entire or lace- 

 rated at their free upper edges, glandular-pubescent or papillose, 

 pale green or almost colourless. 



No. 1. Reniform- triangular, subhastate, cuspidate, acute, five- 

 nerved at the base, alternately nerved upwards, and reticulate. 



Rheum palmatum, L. (fig. 621). 



Ovary one-celled, one-ovuled ; ovule basal, erect, orthotropous ; 

 micropyle superior. 



Fruit an achene, surrounded at the very base with the persistent 



W 



FIG. 621. Rheum palmatum. A, achene, x 3: St, style; W, W, W, wings. 

 B, longitudinal section of achene, x 3 : St, style ; W, W, wings ; P, peri- 

 anth. C, transverse section of achene, x 3. 



remains of the perianth, ovoid-trigonous, broadly and thinly three- 

 winged, suddenly tapering to a cuneate base, tipped with the base 

 of the styles, dark brown, glabrous ; wings traversed longitudinally 

 with a nerve running nearer the margin than the attachment, re- 

 ticulate, pale brown. 



Seed trigonous, conical or flask-shaped, suddenly narrowed at 

 the base, gradually narrowed to the apex, conforming in shape to 

 the fruit except the wings, raised into a more or less prominent ridge 



