Cuscuta denticulata

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Cuscuta denticulata
Cuscuta denticulata cropped.jpg

Cuscuta denticulata

Systematics
Asterids
Euasterids I
Order : Nightshade (Solanales)
Family : Bindweed family (Convolvulaceae)
Genre : Silk ( cuscuta )
Type : Cuscuta denticulata
Scientific name
Cuscuta denticulata
Engelm.

Cuscuta denticulata is a species of the genus silk ( Cuscuta ) in the family of wind plants (Convolvulaceae).

description

Cuscuta denticulata is a parasitic plant. Their stems are thread-like and light yellow to cream-colored. The inflorescences are ball-shaped cymes of two to seven (rarely only one or up to twelve) flowers . There are one to three bracts at the base of the flower groups and on the flower stalks . These are membranous, almost round, egg-shaped, rhombic or egg-shaped-lanceolate. The margins are whole or serrated, the tip is pointed to blunt. The flower stalks are 0.5 to 2.2 mm long or can rarely be completely absent.

The flowers buds are usually rounded and rarely pointed. The flowers themselves are usually five-fold, rarely four-fold, 1.8 to 3.1 mm long and membranous. The inflorescence base and the base of the inflorescence are missing fleshy cells, papillae are also not formed. In central ribs of the calyx lobes are laticifers to see. They are arranged in a row and elongated. The calyx lobes overlap at the base, are inverted-egg-shaped, the edges are serrated, the tip rounded. The calyx separates easily from the crown in rehydrated flowers. It is straw yellow, net-like and shiny, bell-shaped to urn-shaped and as long as or almost as long as the crown.

The crown is colored white and turns creamy yellow as it dries. The corolla tube is bell-shaped, 0.6 to 1.5 mm long. The corolla lobes are bent back and are about as long as the tube. They are ovate to broadly elliptical in shape, the edge is serrated irregularly, the tip is rounded.

The stamens do not protrude or only slightly beyond the crown, they are shorter than the corolla lobes. The anthers have a length of 0.25 to 0.4 mm and are almost round to elliptical in shape. The stamens are 0.2 to 0.4 mm long. The pollen grains are 15 to 17.5 µm long. There are scales between the stamens that touch the base of the stamens. They are elongated ovoid, evenly toothed or fringed.

The stylus are unevenly shaped, thread-like and 0.3 to 0.5 mm long and thus 1/3 to 1/2 times as long as the ovary . The scars are head-shaped and spherical.

The fruits are non-popping to irregularly popping, sloping capsules . They are 1.3 to 2.1 × 1 to 2 mm in size, translucent and covered with the withered crown. Each capsule contains only one seed , which is easily released from the capsules. The seeds are spherical to spherical-egg-shaped and 0.85 to 1.1 × 0.82 to 1.1 mm in size. The chalazal end of the seed ( i.e. opposite the micropyle ) is rounded. The hilum is not sunk and measures about 0.1 to 0.2 mm in diameter. The seed coat of dry seeds is pitted; if the seeds are watered, the seed coat becomes papilous. The embryo is enlarged to a spherical shape, the endosperm is already completely used up by the time the seeds are mature.

The flowering period extends from March to October (rarely until December).

Occurrence

Cuscuta denticulata occurs in North America; the distribution area in the United States includes the states of Arizona , California , Colorado , Idaho , Nevada , Utah and Washington . In Mexico , the species occurs in the states of Baja California to the south of the Sierra Juarez and the Sierra de San Pedro Mártir .

ecology

The species parasitizes mainly on Artemisia , Chrysothamnus and Larrea , but also on grape herbs ( Ambrosia ), Report ( Atriplex ), Coleogyne , Covillea , Ericameria , Eriogonum , Gutierrezia , Hymenoclea , Lepidospartum and others.

literature

  • Mihai Costea et al .: Taxonomic status of Cuscuta nevadensis and C. veatchii (Convolvulaceae) in North America . In: Brittonia , Volume 57, Number 3, 2005, pp. 264-272.