50 Introduction to Botany. 



IV. NASTURTIUM. Water Cress. 



(L., nasus tortus, a wry nose, in allusion to the pungent qualities of the genu.) 



Flowers yellow or white. Pods short or elongated, from globular to 

 oblong-linear, terete or nearly so ; valves nerveless. Leaves mostly 

 pinnate or pinnatifid. Seeds in most cases in 2 rows in each cell. 

 Embracing aquatic and marsh species. 



1. Nasturtium officinale, R. Br. (L., officina, workshop.) TRUE WATER 

 CRESS. Petals white, twice as long as the sepals ; pods linear, from 5 to | inch 

 long; leaves with 3-11 odd-pinnate leaflets. Aquatic plants, rooting at the nodes. 

 I n brooks and ditches. 



2. Nasturtium sinuatum, Nutt. (L., sinuatus, curved or wavy.) SPREADING 

 YELLOW CRESS. Flowers yellow, about \ inch broad. Pods linear-oblong, from 

 a to | inch long, on slender pedicels, somewhat elongated. Low diffuse perennials, 

 with lanceolate, oblanceolate, or oblong leaves, pinnatifid into linear or oblong 

 lobes, or merely sinuate-dentate, from 2 to 3 inches long and usually less than an 

 inch in breadth. In moist ground. 



3. Nasturtium pahistre, DC. (L.,palus, a swamp.) MARSH CRESS. Flowers 

 yellow, from to | inch broad. Pods spreading or curved, about | inch long, on 

 pedicels of nearly the same length ; style quite short. Erect, branching annuals or 

 biennials. Lower leaves deeply pinnatifid, lanceolate, or oblanceolate, petioled ; 

 upper leaves sessile or nearly so, dentate or lobed. In wet places or shallow water. 



V. CARDAMINE. Bitter Cress. 



(Greek name of a cress.) 



Flowers white or purple, in racemes or corymbs. Pods linear- 

 elongate, flattened parallel with the partition, usually erect; valves 

 hardly or not at all nerved, dehiscing elastically at maturity. Seeds in 



1 row in each cell, flattened and marginless. 



1. Cardamine Pennsylvania, Muhl. PENNSYLVANIA BITTER CRESS. Erect, 

 stout, or slender stems, 8 inches to 3 feet tall, leafy throughout. Basal leaves 



2 to 6 inches long, pinnately divided into 4-8 pairs of mostly narrow segments, the 

 terminal segment obovate, oval, or nearly orbicular. Flowers white. Pods nar- 

 rowly linear, rather more or less than i inch long. In swamps and wet places. 



2. Cardamine bulbosa, B. S. P. (L., bulbosus, full of bulbs.) BULBOUS CRESS. 

 Erect stems from a tuberous base, simple or sparingly branched ; 6 inches to i^ feet 

 tall. Basal leaves long-petioled, entire, oval to orbicular, sometimes cordate. Stem 

 leaves mostly sessile, oblong or lanceolate, dentate or entire. Flowers white ; petals 

 much longer than the calyx. The linear-lanceolate pods about i inch long. In 

 wet meadows and springs. 



