70 POLYGON AC E^E. 



persistent calyx, a 1 -celled ovary, bearing 2 or 4 styles or stigmas, and a single seed. 

 Stamens 4-12 inserted on the base of.the 3-6-cleft calyx. Rhubarb and buckwheat are 

 the only wellknown plants of this order in cultivation. 



POLYGONUM. 



Calyx 5 parted; the divisions petal-like, persistent in fruit, and surrounding the 

 usually 3-angled akene. Stamens 3 to 8. Styles or stigmas 2 or 3. Herbs with small 

 flowers on jointed pedicels. 



Knot-weed or Yard-grass and Smart-weed belong to this genus. About 25 species are 

 found in California, of which 2 or 3 are introduced weeds. Two or three species are 

 useful forage plants (Saccaline, Knotgrass.) 



RUMEX, L. 



Calyx of 6 sepals; the three outer herbaceous, spreading in fruit; the three inner 

 larger, somewhat petaloid, covering the akene in fruit (then called valves), and often 

 bearing grainlike appendages on the outside. Stamens 6. Styles 3; stigmas tufted. 

 Introduced weeds with small greenish flowers crowded and whorled in panicled racemes. 



The Docks and Sheep-sorrel are examples of this genus. Of the dozen species on this 

 coast, half are introduced weeds. Canaigre, cultivated for the use of tanners, is a kind 

 of Dock, native of this coast (B. hymenosepalus). 



EBIOGONUM, Michx. 



Flowers borne in a many-to-few-flowered calyx-like involucre of united bracts: the 

 pedicels exserted, jointed to the flower, with bractlets at the base: calyx corolla-like, 

 6-parted or deeply 6-cleft: stamens 9: akene triangular. Herbaceous or somewhat 

 woody plants, usually with a woolly or scurfy pubescence: the entire leaves without 

 stipules and mostly radical: juice frequently acid. Over 80 species grow west of the 

 Mississippi, of which over 50 are Californian, mostly Alpine. 



CHOBIZANTHE, R. Br. 



Flowers borne in 1-3 flowered involucres, which have 3-6 awned segments or teeth, 

 the tube ribbed or angled. Stamens 9 (rarely 6 or 3): akene triangular. Annuals branch- 

 ing dichotomously, the leaves few and mostly basal, ternate bracts at the joints. More 

 than 20 species on this coast. 



OXYTHECA, Nutt. 



Flowers borne in few-flowered, pedicellate, awn-tipped or unarmed involucres, 

 Perianth 6-parted: stamens 6: akene commonly lenticular. Slender annuals, branch- 

 ing dichotomously, the leaves in a rosulate tuft at the base, bracts united at the bas? 

 and leaf-like. Halt a dozen species on this coast. 



