420 Mr. Bentuam on the Eriogonez, a Tribe of the Order Polygonacez. 
EXPLANATION OF THE PLATES. 
Tas. XVII. 
Fig. 1. Arrangement of the floral organs in Rheum crassinervium. 
2. Ditto in Rumez alpinus. 
3. Ditto in Atraphaxis spinosa. 
4. Ditto in Kanigia 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. 4. Pistillum. e. Fruit surrounded by the persistent pe- 
rianthium. f. Fruit separate. g. Seed. h. Transverse section of 
the seed. 
11. Chorizanthe membranacea. a. Involucrum. 6. Pericarpium. c. Seed. 
d. Longitudinal section of ditto. 
Tas. XVIII. 
Fig. 1. Eriogonum angulosum. 
2. Eriogonum umbellatum. 
Tas. 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. 
Tas. XX. 
Fig. 1. Mucronea californica. a. Involucrum. 6. Perianthium. 
