"Calopogon," says Professor Robertson, who knows more about the fertilization of American wild flowers by insects than most writers, "is one of a few flowers which move the insect toward the stigma.... There is no expenditure in keeping up a supply of nectar, and the flower, although requiring a smooth insect of a certain size and weight, suffers nothing from the visits of those it cannot utilize. Then, there is no delay caused by the insect waiting to suck; but as soon as it alights it is thrown down against the stigma. This occurs so quickly that, while standing net in hand, I have seen insects effect pollination and escape before I could catch them. So many orchids fasten their pollinia upon the faces and tongues of insects that it is interesting to find one which applies them regularly to the first abdominal segment. Mr. Darwin has observed that absence of hair on the tongues of Lepidoptera (butterflies and moths) and on the faces of Hymenoptera (bees; wasps, etc.) has led to the more usual adaptations, and sparseness of hair has its influence in this case. Species of Augochlora are the only insects on which I found pollinia. These bees are very smooth, depending for ornament on the metallic sheen of their bodies. An Halictus repeatedly pulled down the labella (lips) of flowers from which pollinia had not been removed; and the only reason I can assign for its failure to extract pollinia is that it is more hairy than the Augochlora. COMMON PERSICARIA, PINK KNOTWEED, or JOINT-WEED; SMARTWEED (Polygonum Pennsylvanicum) Buckwheat family Flowers - Very small, pink, collected in terminal, dense, narrow, obtuse spikes, 1 to 2 in. long. Calyx pink or greenish, 5-parted, like petals; no corolla; stamens 8 or less; style 2-parted. Stem: 1 to 3 ft. high, simple or branched, often partly red, the joints swollen and sheathed; the branches above, and peduncles glandular. Leaves: Oblong, lance-shaped, entire edged, 2 to 11 in. long, with stout midrib, sharply tapering at tip, rounded into short petioles below. Preferred Habitat - Waste places, roadsides, moist soil. Flowering Season - July-October. Distribution - Nova Scotia to the Gulf of Mexico; westward to Texas and Minnesota.