Polydora serratuloides (DC.) H.Rob.

Global description

Polydora serratuloides is an erect plant with abundant branching in its upper part. It has linear to filiform leaves arranged in a tight spiral. At the end of each branch is an ovoid capitulum. The flowers are tubular and purplish red. The achenes are ribbed, pubescent and glandular and surmounted by a pappus formed of scales and long silks.

Cotyledons

Cotyledons are reduced. They are obovate in shape and 5 mm long.

First leaves

The first leaves are alternate and simple. The first grows 1 cm above the cotyledons. They are sessile, filiform and 1 cm long and 1 mm wide.

General habit

Polydora serratuloides is erect. The plant is abundantly branched especially in the upper part. It is usually 30 to 60 cm high but can reach 100 cm in high humidity conditions.

Underground system

The root consists of a strong taproot, often woody in older plants.

Stem

The stem is solid, fluted and finely pubescent. It is often woody at the base in older plants.

Leaf

The leaves are alternate and simple. They are sessile. The lamina is linear to filiform, with an acute corner vertex. It is 30 to 50 mm long and 1 to 4 mm wide. The margin is recurved on the side of the lower face. The central rib is strongly prominent on the underside. Both sides are slightly scabrous. The leaves are arranged in a tight spiral throughout the stem and twigs.

Inflorescence

The flowers are assembled in solitary flower heads at the end of each branch. These flower heads are ovoid and 15 mm long and 10 mm in diameter. They are surrounded by an involucre that includes several rows of bracts. These are lanceolate and covered with a strong white pubescence. The apex is sharp and dark in color, creating small, dark points that stand out against the clear bracts. All the flowers of the capitulum are tubulated. They do not exceed the involucre. The corolla is purplish red and ends with 5 teeth.

Fruit

The fruit is a fusiform achene with 5 or 6 longitudinal wrinkles. The peaks of the wrinkles are pubescent while the troughs are filled with small glands. The achene is light brown. It is surmounted by a pappus. It consists of an outer row of short white scales and an inner row of finely pubescent bristles 6 to 7 mm long.

https://www.gbif.org/fr/species/5397613