MUSTARD FAMILY 



CRUCIFERAE 



TRUE WATER CRESS 



Radicula Nasturtium-aquaticum (L.) Britten & Rendle 



It frequently happens that when a plant is introduced 

 into a new country whose climate is agreeable it finds 

 conditions for growth and reproduction unusually favor- 

 able, partly because it is freed from com- 

 petition with many of its natural enemies. 

 Under such circumstances many plants 

 become pernicious weeds. 



This Water Cress could hardly be 

 called a weed but it is an introduced plant 

 which has spread over most of the central 

 part of the continent and is 

 common in most places. It 

 is a native of Europe and 

 northern Asia, and is now 

 found in the West Indies 

 and South America as well. 

 It is greatly prized and ex- 

 tensively used as a salad, 

 for which purpose it was 

 originally cultivated. 



True Water Cress grows in the water 

 of [brooks and streams and forms very 

 dense patches of considerable size. The 

 smooth stems float on the water or creep on the mud, branching 

 freely and rooting at the nodes. Leaflets of the pinnately com- 

 pound leaves are 3-1 1, obtuse, ovate or oval, or the larger 

 terminal one somewhat circular. 



The small white flowers have the usual structure oi flowers 

 of this family, and the petals are about twice as long as the 

 sepals. The pods, turned upward from the slender pedicels of 

 equal length, are divided longitudinally into 2 parts, each of 

 which contains 1 rows of seeds. 



The Marsh Cress or Yellow Swamp Cress, Radicula palustris (L.) 

 Moench, is common in wet places or shallow water. The smooth 

 erect stem is 8-32 inches high and much branched. Leaves are 

 pinnately cleft or more deeply parted; the upper may be deeply 

 narrow lobed. The small orange-yellow flowers are on pedicels as 

 short as the flower but longer than the ellipsoid-cylindric pods. The 

 blooming season is May to August. 



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