August 10, 2015
Rorippa palustris L. (Bess)
Tap-rooted annual or biennial. Occasionally, a weak perennial.
Alternate, variably shaped leaves initially develop from a basal rosette. Leaves are deeply lobed with a large terminal lobe and three to seven other lobes. The upper stem leaves are smaller with lobed to toothed margins and, occasionally, winged petioles with earlobe-shaped bases.
Branched or unbranched stems arise from a basal rosette to flower, usually less than 2 feet in height.
Flowers and fruit
Small, light yellow flowers with four petals are found in terminal clusters. Fruit are small, globe- to short cylinder-shaped capsules with a slight upward curve. Each capsule contains numerous, tiny, yellowish brown seeds.
Yellow fieldcress [Rorippa sylvestris (L.) Bess.] Differs by having a perennial nature with prolific, aggressive creeping roots and more deeply lobed leaves. Flowers are more conspicuous and brightly colored. Capsules are smaller and usually do not contain seeds.
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