Cardamine hirsuta L.

Global description

Cardamine hirsuta is a small annual erect plant, reaching 35 cm tall, but often smaller. The leaves are in regular rosette at the base and alternate along the stem. They are simple but deeply and regularly lobed, with 1 to 5 pairs of opposite side lobes and 1 rounded terminal lobe, to such extent that it resemble compound leaves. The leaves carried by the stems are shorter, containing fewer and more elongated lobes. The inflorescence consists of terminal clusters made up of a small or a large number of small white flowers, with 4 petals. The fruits are linear pods, 2 cm long and 1 mm wide, opening from the base by two valves at maturity, releasing all the small seeds.
 
Cotyledons
 
Cotyledons are shortly stalked with a spatulate lamina. They are 5 mm long and 2.5 mm wide. They are sparsely covered with hairs.
 
First leaves
  
The first leaves are simple, arranged in a basal rosette. They are held by a petiole of 0.5 to 2 cm long. The leaf blades is subcircular, cordate at base and sparsely covered with hairs. As from the fifth to eighth leaf, the first side lobes appear.

General habit
 
Small herbaceous plant, rosette at the base, with erect branches, 15 to 35 cm high.
 
Underground system
 
The plant has a taproot system.
 
Stem
 
The stem is circular to polygonal, hollow, glabrous or covered with long hairs.
 
Leaf
 
The leaves are simple, rapidly deeply lobed up to the central rib, and looking like imparipinnate compound leaves. The basal leaves are arranged in rosettes and are often already dry at the time of anthesis. They are held by a flat, ciliated or glabrous petiole, 4 to 8 cm long and formed of 1 to 5 pairs of sub-opposite lobes, looking like leaflets. The leaf blade is bipennatifid. The side lobes are obovate to circular, sometimes slightly tri-lobed, with a rounded tip and rounded or wedged base. The terminal lobe is circular to kidney-shaped, sometimes slightly tri or penta-lobed, with rounded tip and cordate base. The upper surface is hairy. The caulinary leaves are few in numbers, similar to basal leaves but are smaller and with narrower leaflets.

Inflorescence
 
The inflorescence consists of terminal clusters, mostly consisting densely of fruits. Few to many small flowers.
 
Flower
 
The flowers do not exceed 4 mm in diameter, and are white in color and consist of 4 small lanceolate sepals, 4 spatulate petals of 2 to 3 mm long, and 4 stamens.
 
Fruit
 
The fruit is a long linear siliqua of 1.5 to 2 cm and 1 mm wide, erect, exceeding the flowers, dehiscent. Smooth valves opening at maturity from the base that move away from the central partition by remaining fixed at the top of the siliqua.
 
Seed
 
The seed is lenticular to flattened oblong, 1 mm in diameter, and narrowly winged.

Origin

Cardamine hirsuta is native to Europe, North and Central Africa, from the Arabian Peninsula to China.

Worldwide distribution

This species has been introduced to North and South America, South Africa and certain islands in the Indian Ocean (Réunion, Mauritius, Seychelles), Australia, New Zealand and New Caledonia.

https://www.gbif.org/species/3046258