420 Mr. Bentham om the Eriogonese, a Tribe of the Order Polygonacese. 



EXPLANATION OF THE PLATES. 



Tab. XVIL 



Fig. 1. Arrangement of the floral organs in Rheum crassinervium. 



2. Ditto in Rumex alpinus. 



3. Ditto in Atraphaxis spinosa. 



4. Ditto in Kcenigia islandica. 



5. Ditto in Polygonum alpinum. 



6. Ditto in Polygonum Convolvulus. 



7 & 8. Ditto in Polygonum Persicaria. 

 9. Ditto in Polygonum virginianum. 



10. Eriogonum compositum. a. Involucrum. b. Flower, c. Perianthium 



laid open. d. Pistillum. e. Fruit surrounded by the persistent pe- 

 rianthium. /. Fruit separate, g. Seed. h. Transverse section of 

 the seed. 



11. Chorizanthe membranacea. a. Involucrum. 6. Pericarpium. c. Seed. 



d. Longitudinal section of ditto. 



Tab. XVIII. 



Fig. 1 . Eriogonum angulosum. 

 2. Eriogonum umbellatum. 



Tab. XIX. 



Fig. 1. Chorizanthe virgata. a. Involucrum. b. Perianthium. 



2. Chorizanthe pungens. a. Involucrum. b. The same laid open. c. Pe- 

 rianthium. d. The same laid open, with the stamens, e. Pistillum. 



Tab. XX. 

 Fig. 1. Mucronea califomica. a. Involucrum. b. Perianthium. 



