Fig. 413: Polygonum Hydropiper: a, perianth enclosing mature fruit, x 6; b, tip 

 of spike, showing the glandular-punctate flowers and the funnelform ciliate sheathing 

 bracts, x 4; c, young flower, x 6; d, opened perianth, showing the glands of the disk 

 and the longer filaments inserted between them, x 6; e, mature achene, trigonous type, 

 x 6; f, mature achene, trigonous type (cross section), x 6; g, mature achene, semi- 

 lenticular type (cross section), x 6; h, mature achene, semilenticular type, x 6; i, 

 stipular leaf sheath, showing coarsely ciliate apex, x 2Vo; j, habit, basal part of plant, 

 showing the roots and the stems swollen above the nodes, x %; k, habit, upper part of 

 plant, showing the successively smaller leaves and the variable spikes, x %. (From 

 Mason, Fig. 201). 



