Nomenclature

Species name:

Centranthus calcitrapae   (L.) Dufr.

Author(s):

Carl von Linné
   Sweden, 1707-1778

Pierre Dufresne
   Frrance, 1786-1836

Common name:

Annual Valerian
Cut-leaved Valerian
Pink Valerian

Maltese name:

Valerjana Roza

Plant Family:

Valerianaceae   (Valerian Family)

Name Derivation:

Centranthus = From the Greek 'kentron' (=spur) and 'anthos' (=flower); referring to the flower which have a spur-like base (Greek);

calcitrapa = From the Latin calcitro, "to kick," caltrop (or crow's foot), a four-pointed weapon usually positioned on the ground to impede enemy movements. It is not well understood to what part of plant is referenced to but probably to the seed. (Latin).

Synonyms:

Centranthus clausonis, Centranthus pinnatifidus, Valeriana calcitrapa

Plant Description

Life Cycle:

Annual

Habitat:

Rocky places especially near valleys.

Sources in Malta:

Locally frequent in a restricted number of sites. Examples include Wied il-Qirda, Mgarr ix-Xini and Wied Anglu.

Plant Height:

5-40cm

Flowering Time:

Mar-May

This multi-flowering plant is attributed to rocky places and garigues especially those forming valley sides. This annual plant consists of a branched or unbranched hollowed and glabrous stem that can grow about 40cm long, but usually it is shorter; depending soil depth.

The upper leaves are opposite and pinnatifid with rounded elongated lobes, where the terminal lobe is the largest. Lobe margin is usually smooth but in few specimen it is slightly serrated. Lower leaves are petiolated (stalked) and less pinnatifid (forming an immaginary obovate lamina). The leaves in between are an intermediate between the upper and lower leaf forms.

The plant forms numerous tiny flowers in dense dichasial cymes. Each flower has a calyx of many teeth-like or linear structures that play an important role in seed dispersion. At the flowering stage, these are rolled inside and not much visible as 'teeth'. The pink or lilac corolla consists of a 1-2mm tube-like structure at one end which opens to 5 tiny (1mm) unequal, lance-shaped lobes (= petals) at the other end. On closer examination, the corolla tube has a swollen structure at its underside which is often referred to as a spur. This is not longer from the tip of the corolla tube. This gibbous structure distinguishes Centranthus from other Valerianacea genera (found on the Maltese islands) which lack it.

The ovary is a small, rounded structure found inside the corolla tube with a simple style ending in a two-lobed stigma. It possess one fertile locule and 2 sterile ones. The male reproductive part is reduced to a single stamen that is seen projecting out from the corolla mouth. It has a darker colour from the corolla and produces yellow pollen.

After fertilisation the ovary develops into a cypsela, a special type of fruit which consists of a single seed and surmounted by the calyx. During the fruiting stage, the calyical teeth spread out forming a bristly pappus which helps the small and lightseed to get dispered away by wind.

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