206 THE AMERICAN NATURALIST. [Vor. XXXV. 
Conspicuousness is gained by the union of the flowers in axil- 
lary or terminal clusters. The green flowers are very small, 
odorless and honeyless, and self-fertilized. The white and red 
are more conspicuous, may contain honey, and are visited by 
few or numerous insects; for instance, P. persicaria has a 
white or red calyx, secretes honey sparingly, and is visited by 
many flies and small bees. The species of this genus most 
excellently illustrate the successive steps by which a green 
perianth may become conspicuous. In the common door-weed 
(P. aviculare) the margins of the sepals are white, turning 
pink, while the centers remain green. The flowers are self- 
fertilized, but are occasionally visited by flies. In P. convol- 
vulus the two inner divisions of the perianth are entirely white, 
but the outer are keeled with green; the calyx of P. virgini- 
anum is usually green, tinged or tipped with white; P. persz-. 
carta has in the same spike green, white, and red flowers ; 
while P. orientale, cultivated from India, has large, bright rose- 
colored flowers. In the case of the familiar buckwheat (Fago- 
yrum fagopyrum) the waving fields of white bloom are very 
conspicuous. The dimorphic flowers possess perfume, and 
insects manifest special preference for the honey; in Germany 
Müller has enumerated forty-one visitors, of which twelve are 
bees.  Cross-fertilization is insured and self-fertilization ren- 
dered difficult. The marked tendency of both the vegetative 
and floral organs in this family to develop reddish coloration is 
evidently due to bright sunlight and the chemical constitution 
of the sap, for the Alpine bistort (P. viviparum) of the White 
Mountains often has little red bulblets in place of the flesh- 
colored flowers. In P. scandans and P. dumetorum the calyx | 
is yellowish-green. 
The Chenopodiacez is a large family consisting chiefly of 
herbs of a homely aspect. To it belong the garden beet and 
the pot-herb spinach. The green flowers are very small, usu- 
ally clustered, and in many species unisexual. The calyx is 
usually present, but is wanting in the pistillate forms of some 
genera. As in the Polygonacez, certain species show a tend- 
ency to develop red coloration; Chenopodium rubrum has a 
red calyx, and the inflorescence of C. album often turns reddish 
