POLYGONACEiE. (BUCKWHEAT FAMILY.) 31o 



Order 66. POLYGONACE^E. (Buckwiikat Family.) 



Herbs, with alternate and entire leaves, or sj.nietiincs vcrtirillato, and 

 stipules in the form of slicaths above the swidlcn joints (»f tlu- hIimm or 

 none; flowers mostly perfect, with a more or less persistent tuilyx, a 

 1 -celled ovary bearing 2 or 3 styles or stigmas, and a single erect srrd ; 

 stamens mostly 4 to 9. Flowers rather small, the perianth of :i ti, (J 

 segments, the inner ones or all usually petaloid ; fruit an akeuc. 



♦ Flowers iuvolucrate: stamens 9: styles :?, with cajiitjite stipiuw : herbs or woody at ba»e, 



with alternate or verticillate leaves, without stiinilea. 

 1. £rlog:onuni. Involucre several-flowered, with 4 to 8 pointless teeth. Flowen ex- 



serteil. Akene mostly 3-angled. Annuals or perennials. 

 '2. Oxytheca. Involucre few-flowered, herbaceous, with 3 to 5 straight arute or usually 



awned lobes. Flowers on exserted pedicels. Akeiie lentifular. Bra.u t«-niat4v 



Annuals. 



« ♦ Flowers without involucre : stamens 4 to 8 : styles 2 or 3 : herbs with alt«niatfi le«ve« 

 and scarious sheathing stipules ; juice usually acid, acrid or pungent. 



3. Oxyria. Sepals 4, the outer smaller and spreading. Stigmas 2, tufted. Akene orblcu- 



lar-winged. Leaves reniform. 



4. Rumex. Sepals 6, the outer spreading, the inner enlarging and appressed to the trian 



gular akene. Stigmas 3, tufted. 



5. Polygonum. Sepals 4 to 6, equal, appressed to the triangular or lenticular akene 



Styles 2 or 3 : stigmas capitate. 



1. ERIOGONUM, Michx. 



Involucre campanulate, turbinate or oblong. Perianth 6-parted, colnro*!. 

 enclosing the akene. — Herbaceous or somewhat woody, witii radital or alter- 

 nate or verticillate leaves. 



§ 1 . Involucres more or less broadli/ turbinate, not nerved or angled, 4 to 8-toot/ifd 



or lobed : bracts foUaceous, roreli/ somewhat ternate. 



* xike7ies membranoHsl 11 winrjed. 



1. E. alatum, Torr. Loosely silky-villous thronghout, or the leaved 



nearly glabrous except on the margin and midrib : leaves alternate. l<>ng, oIh 



lauceolate : involucres pedunculate, solitary, with .5 erect teeth : tltnvers a line 



long, yellow, nearly glabrous, abrupt at base : akene winged the whole length 



— From Arizona and Texas to Nebraska. 



* * Akenes not icinged. 



■t- Floicers rjlabrous. 



'2. E. umbellatum, Torr. Tomentose: leaves glabrate ab«ivp or pla- 



brous, oblaiiceolate or sjiatnlato: involucres deeply lubed ; l«»be.«» becuming 



reflexed : umbel simple, of 2 to 10 naked raifs, on nahd (rareh/ l-i>rarted) ftfdun- 



cles. — From Colorado to Orejion and California. 



Var. monocephalum, Torr. .^ (Iray. A reduced dwarf al|.iiio f..rm. 

 the naked or bractcatc ]ic(luiuk' bearing: a solitary inv<ducre: leaves .nmall. 



3. E. heracleoides, Xutt. Similar, but the indnnrlr u$Hnll;i verticillate- 

 hracted: leaves narrower, mostli/ somewhat revolute or nndulittc : umbel 6- (I-IM 



