POLYGCWUM. 201 



The Flowers, small and numerous, are supported on 

 pedicels ; hence the cluster, which seems from its density a 

 spike, is properly a raceme. They are regular, but very un- 

 symmetrical, consisting of 5 sepals, 6 stamens, 2 stigmas and 

 1 ovary. Like the flowers of Hepatica (p. 55) they are apet- 

 alous, having but one set of envelopes. 



The J^rmt. The ovary ripens into a lens-shaped, black, 

 polished achenium still inclosed in the persistent, rose-col- 

 ored calyx. The one seed contains a curved, inverted 

 embryo on the side of a starchy albumen. 



The Name. Polygonum Persicdria is the classic name, 

 the former meaning many- jointed (Gr. polys, many, gone, 

 joints) ; the latter, peach-leaved, alluding to the resemblance 

 of the leaves to those of the Peach-tree (Persica, Tournef.). 

 Other species of Polygonum will also be found flowering in 

 June and July, and may be profitably studied with this, to 

 mark the distinctive specific characters of each, viz. : 



P. Pennsylvdnicum, the Pennsylvanian Knotweed, a na- 

 tive species growing in wet places, has the Tipper parts beset 

 with minute glandular hairs (glandular-hispid), the flowers 

 in dense racemes, stamens 8, etc. 



P. aviculare, the Bird Knotweed, prostrate in dooryards, 

 has small (!' and less) leaves, and minute axillary flowers. 

 The seeds furnish food for many wild birds. 



P. ampliiUum (amphibious) grows either in water, or on 

 land. It is our largest native species, with leaves 5-7' long 

 and bright red flowers in thick spikes 1-2' long. Stamens 

 only 5. It is smooth when growing in water, viscid-hairy, 

 on land.* 



* The beautiful rosy petals of Polygonum amphibium are rich in honey. The 

 stamens, however, are short, and the pistil projects above the corolla. The nectar is 

 unprotected and accessible even to small insects like the ant. The stamens ripen 

 before the pistil, and any flying insect, however small, coming from above would 

 assist in cross-fertilization. Creeping insects, on the contrary, would rob the honey 



