Cuscuta liliputana
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| Costea & Stefanovic |
Cuscuta liliputana is a parasitic plant of the genus silk ( Cuscuta ) in the family of wind plants (Convolvulaceae). The distribution areas of the species are in the southern United States and possibly in Mexico .
description
Cuscuta liliputana have slender, yellow to orange colored stems . The inflorescences are umbel-shaped cymes of usually two to eleven, rarely just one flower . At the base of the flower groups there is a bract , at the base of the flower stalks there can also be a bract. The bracts are fleshy, ovate-lanceolate, with entire margins and pointed forward. The flower stalks are usually 2 to 3 mm, rarely 1 to 5 mm long, mostly they are covered with papillae .
The flowers are usually four-fold, rarely only three-fold. They are off-white and turn off-white as they dry. Sepals and crown may be papillous, latex does not exist or hardly in the midrib of the corolla. The calyx has a length of 1.3 to 1.7 mm, it is straw-yellow, somewhat reticulate and shiny, cylindrical and about as long as the corolla tube. The sepals are free from each other for about 3/4 of their length. The calyx tube is 0.3 to 0.7 mm long, the calyx lobes 1 to 1.35 mm long. Their edge is entire, the tip is pointed or pointed, they do not overlap and are oval-triangular in shape. The crown is white, 3 to 3.6 mm long, of which the cylindrical corolla tube makes up about 1.5 to 2 mm. The corolla lobes are 1.3 to 1.65 mm long, initially upright, later protruding or bent back. They are lanceolate, with entire margins, tapering towards the front. The epicuticular wax forms a pattern of longitudinal, net-like rods.
The stamens protrude beyond the corolla tube, but are shorter than the corolla lobes. The anthers are broad to narrowly elliptical, 0.35 to 0.5 mm long and 0.2 to 0.35 mm wide. The stamens are 0.5 to 0.8 mm long. The pollen grains are 24 to 28 µm long, trizonocolpat and prolate. The tectum is not perforated or only slightly dotted, the patterns are grainy-conical. Between the stamens there are scales that are cut off to slightly inverted egg-shaped, have a length of 1/4 to 1/3 the length of the corolla tube, i.e. 0.6 to 0.8 mm and 0.1 to 0.2 mm a fabric band of 0.1 to 0.18 mm long fringes are connected to one another. The two styles are evenly thread-shaped, 0.8 to 2.5 mm long and thus longer than the ovary . The scars are spherical head-shaped.
The fruits are capsules that burst open with a ring crack . They are 1.5 to 2.2 mm long, 0.75 to 2.5 mm wide, their shape is spherical or indented spherical. At the front they are thickened and somewhat raised, or provided with two to four humps, which are arranged around small appendages emerging from the styluses. The fruits are translucent and bear the wilting crown. Each capsule contains two to four angled seeds that can be nearly round to broadly elliptical. They are 0.8 to 1.5 × 0.7 to 0.85 mm in size, the seed coat is pitted papillae. The hilum is almost terminal and measures 0.15 to 0.18 mm in diameter.
Occurrence, locations and ecology
The species is native to southern New Mexico , Arizona and southwest Texas , and the distribution probably extends to Mexico . The known locations are at altitudes between 30 m (in Texas) up to 1680 m (in New Mexico). The hosts of the species belong to the subgenus Chamaesyce of the genus milkweed ( Euphorbia ), which grows mainly in disturbed locations in dry valleys of deserts, in sand and fine gravel.
Systematics and botanical history
Cuscuta liliputana is classified within the genus Silk ( Cuscuta ) in the subgenus Grammica . The species is probably a naturally occurring hybrid whose parent species probably consist of a species close to Cuscuta umbellata var. Reflexa , Cuscuta odontolepsis and Cuscuta acuta and a species close to Cuscuta umbellata and Cuscuta hyalina .
The species was first described in 2008 by Mihai Costea and Saša Stefanovic . The epithet is derived from the small size of the plant and the flowers and is reminiscent of the imaginary land Liliput from Jonathan Swift's work Gulliver's Travels .
literature
- Sasa Stefanovic and Mihai Costea: Reticulate evolution in the parasitic genus Cuscuta (Convolvulaceae): over and over again (PDF; 1.0 MB) . In: Botany , Volume 86, 2008. Pages 791-808.