Planodes
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Planodes is a small genus of plants in the cruciferous family(Brassicaceae). The range of the two species is on the North American continent in the southern half of the USA and in Mexico .
description
Vegetative characteristics
The two Planodes species grow as annual , herbaceous plants . The two species differ, for example, in that Planodes mexicanum is bald and Planodes virginicum has simple hairs ( trichomes ). The upright to lying stems are unbranched or branched at the base and / or towards the tip.
The leaves are either short-stalked and not eyelet distributed on the stem or stalked in basal rosettes at the base of the stem. The basal leaves have a leaf blade that is pinnately lobed or deeply lobed with egg-shaped to lanceolate lobes. The leaf margins are smooth or serrated. The less divided stem leaves have serrated leaf margins towards the tip of the leaf.
Generative characteristics
Many flowers stand together in an umbrella-clusters of inflorescences that extend considerably to fruit ripe and contain no bracts . The inflorescence axis is straight and the durable flower stalks are sparsely spreading and ascending.
The hermaphrodite flowers are fourfold. Of the four upright, elongated sepals , the lateral ones are not sack-shaped at the base. The petals are longer than the sepals. The four white petals are inverted-lanceolate with a blunt tip and their nail is not separated from the blade. There are six upright stamens in two slightly different lengths in a 4: 2 ratio. The egg-shaped anthers are not pointed. There is one sap gland on each side of the lateral stamens and the middle sap glands are missing. Each ovary contains 20 till 44 ovules . The stylus , which is up to 0.5 millimeters long, ends in a cephalic, bald scar .
The inelastic, elongated, flattened, unsegmented pods have flat, constricted, paper-like, bald flaps with an indistinct central nerve. There is a rudimentary gynophore . The placental frame is rounded and wingless. The membranous and unveined partitions are fully developed. The almost circular, flattened, winged seeds are laid out in one row. The seed coat does not become slimy and sticky when wet.
The position of the root system in comparison to the cotyledons is pleurorrhizal or lateral roots .
The basic chromosome number is x = 8.
Systematics
The generic name Planodes is derived from the Greek planis for wanderer and -odes for similarity and alludes to the previous assignments to other genera.
The genus Planodes was set up in 1912 by Edward Lee Greene in Leaflets of Botanical Observation and Criticism , Volume 2, pp. 220-221 to include Cardamine virginica L. as the only species of the genus. Ihsan Ali Al-Shehbaz & al placed it in 2006 in the tribe Cardamineae within the family of the cruciferous plants (Brassicaceae). In 2010, however, with Arabis mexicana, another species was added to this genus, so that the following two species now belong to it:
- Planodes mexicanum ( S. Watson ) Al-Shehbaz (Syn. Arabis mexicana S. Watson , Sibara mexicana ( S. Watson ) Rollins ): distribution in Mexico
- Planodes virginicum (L.) Greene (Syn .: Arabis virginica (L.) Poir. , Cardamine virginica L. , Sibara virginica (L.) Rollins ): Distribution in the USA and Mexico
swell
literature
- Ihsan A. Al-Shehbaz: Arabis mexicana Belongs to Planodes (Brassicaceae) . In: Harvard Papers in Botany . tape 15 , no. 1 , June 2010, ISSN 1043-4534 , p. 137-138 , doi : 10.3100 / 025.015.0106 (English).
Individual evidence
- ↑ Ihsan A. Al-Shehbaz: Magnoliophyta: Salicaceae to Brassicaceae . Brassicaceae. In: Flora of North America Editorial Committee (Ed.): Flora of North America . tape 7 . Oxford University Press, New York et al. 2010, ISBN 978-0-19-531822-7 , Planodes Greene, pp. 492 (English, online [accessed on May 28, 2011] section description and distribution).