1 52 FLOWERS OF LAKES, RIVERS, ETC. 



Arrow-head (Sagittaria sagittifolia, L.) 



Remains of this typical aquatic and arctic type are found in Inter- 

 glacial beds at West Wittering in Sussex. To-day it is found in 

 Arctic Europe (except Greece), N. Asia, N. W. India in the North 

 Temperate and Arctic Zones. In Great Britain it is absent in Corn- 

 wall and N. Devon from the Peninsula province, and in the Channel 

 from the Isle of Wight, occurring throughout the Thames and Anglia; 

 in the Severn, not in Monmouth; in S. Wales only in Pembroke; in 

 N. Wales in Denbigh, Flint, Anglesea; and in the Trent province and 

 Mersey except in Mid Lanes; in the Humber province; only in 

 Durham in the Tyne province; not in the Isle of Man in the Lakes 

 province, and in Renfrew and Lanark. Elsewhere it ranges from 

 Cumberland to Kent and Devon. It is naturalized in Scotland, local 

 in Ireland. 



Arrow-head is always the associate of Water Plantain, Flowering 

 Rush, and pondweeds of different kinds, being aquatic, and likewise 

 found in both still and running water, growing in ponds and lakes, and 

 also in rivers and streams. Canals are also a favourite habitat, since 

 they are intermediate between stagnant and flowing water. The plant 

 grows in the reecl swamp. 



A floating plant with erect leaves and scapes only in later stages, 

 the Latin names and the English at once point to its main character- 

 istic, the arrow-shaped leaves, which are at first lance-shaped, with a 

 long point, with long lobes, borne on long 3-angled leaf-stalks. The 

 early submerged leaves are linear and streaming. The stems are 

 stolon iferous, the stolons or creeping shoots forming winter buds, and 

 also, like the main stem, tubers. 



The flowers are white on simple scapes, in whorls, with purple 

 anthers in the centre, and the petals have also a purple claw. The 

 male flowers are larger. The carpels are flattened at the sides and 

 winged. 



The plant is 2-8 in. in height. Arrow-head flowers from July 

 up to September, and is perennial, propagated by division. 



The flowers resemble those in Alisma, but are unisexual, diclinous, 

 racemose, and the male flowers are above the female. The anthers 

 are purple and dehisce laterally, there being many stamens. The 

 female flowers are also variable. They are visited by flies, and contain 

 honey. 



The carpels are numerous, the smooth seeds falling when ripe 



