rachis

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Related to rachises: rachial

ra·chis

 (rā′kĭs)
n. pl. ra·chis·es or rach·i·des (răk′ĭ-dēz′, rā′kĭ-)
1.
a. The main stem of an elongated inflorescence, as in a grass.
b. The main axis of a pinnately compound leaf or of a fern frond.
2. The main shaft of a bird's feather, especially the part to which the barbs are attached.
3. The spinal column.

[New Latin, from Greek rhakhis, spine, ridge.]

ra′chi·al adj.

rachis

(ˈreɪkɪs) or

rhachis

n, pl rachises, rhachises, rachides or rhachides (ˈrækɪˌdiːz; ˈreɪ-)
1. (Botany) botany the main axis or stem of an inflorescence or compound leaf
2. (Zoology) ornithol the shaft of a feather, esp the part that carries the barbs
3. (Anatomy) another name for spinal column
[C17: via New Latin from Greek rhakhis ridge]
rachial, rhachial rachidial, rhachidial adj

ra•chis

(ˈreɪ kɪs)

n., pl. ra•chis•es, rach•i•des (ˈræk ɪˌdiz, ˈreɪ kɪ-)
1. any of various axial structures of a plant, as the stem of a leaflet.
2. the part of the shaft of a feather bearing the web.
[1775–85; < New Latin < Greek rháchis spine]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.rachis - axis of a compound leaf or compound inflorescencerachis - axis of a compound leaf or compound inflorescence
axis - the main stem or central part about which plant organs or plant parts such as branches are arranged
2.rachis - the series of vertebrae forming the axis of the skeleton and protecting the spinal cordrachis - the series of vertebrae forming the axis of the skeleton and protecting the spinal cord; "the fall broke his back"
notochord - a flexible rodlike structure that forms the supporting axis of the body in the lowest chordates and lowest vertebrates and in embryos of higher vertebrates
chine - backbone of an animal
canalis vertebralis, spinal canal, vertebral canal - the canal in successive vertebrae through which the spinal cord passes
coccyx, tail bone - the end of the vertebral column in humans and tailless apes
vertebra - one of the bony segments of the spinal column
intervertebral disc, intervertebral disk - a fibrocartilaginous disc serving as a cushion between all of the vertebrae of the spinal column (except between the first two)
skeletal structure - any structure created by the skeleton of an organism
axial skeleton - the part of the skeleton that includes the skull and spinal column and sternum and ribs
Translations

ra·chis

n. raquis, la columna vertebral.
References in periodicals archive ?
Its species differ from others in the genus by having a distinctive type of hair within the grooves of the rachises and costae adaxially.
When multiple rachises and fruit with sugar accumulation disorder were tested for minerals, the only consistent difference from normally developing fruit or rachises was increased calcium in the rachis tissue (Krasnow et al.
apex; their rachises are grooved, and slightly winged.
Fronds broader than long, fan-like; main rachis forked at the tip; leaflets borne on one side of the forked rachises.
5 m long, basally 3-pinnate-pinnatisect, medially 2-pinnate-pinnatisect; lamina rachises pubescent abaxially; basal pinnae up to 30 cm long, inequilateral; pinna rachises abaxially sparsely glandular, pubescent, scaly, the glands ca.
4 g (n = 5) and was composed mainly of mosses (60%), and fern rachises and dry roots (40%).
This specimen resembles Megalastrum aureisquama but differs by dark appressed scales along the lamina rachises (not golden brown scales).
The nest was lined mostly with thin dark fibers of Spanish moss (Tillandsia usneoides) and rachises (< 1 mm in diam) of pinnate leaves (Leguminosae), accompanied by small fragments of dry leaves, shredded bark, an insect wing, small twigs, fungal mycelia, and fragments of snake skin.
Other characters found in nearly all species of Megalastrum are erect or decumbent rhizomes, basal pinnae prolonged on the basiscopic side, pinna rachises and costules adaxially pubescent, and vein tips enlarged (hydathodous).