What is a rachis in botany?
In botany. In plants, a rachis is the main axis of a compound structure. It can be the main stem of a compound leaf, such as in Acacia or ferns, or the main, flower-bearing portion of an inflorescence above a supporting peduncle . A ripe head of wild-type wheat is easily shattered into dispersal units when touched or blown by the wind.
What is a rachis on a Dinosaur Feather?
Current dinosaur feather fossils don't have a rachis; instead, the specimens show that dinos' feathers acted as a layer of warmth to protect against the elements. — Daisy Hernandez, Popular Mechanics, 5 Aug. 2019 According to Persons, flight feathers found on bird wings contain a hollow center called the rachis, from which the barbs protrude.
What is the rachis of the vertebral column?
In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually forms the supporting axis of the body and is then called the spine or vertebral column. Rachis can also mean the central shaft of pennaceous feathers.
What is the dominant gene for rachis?
Other dominant genes are Br2 and Br3 on chromosomes 3A and 3B, respectively [90,95,97]. The mature spike rachis of wild emmer disarticulates spontaneously between each spikelet leading to the dispersion of wedge-type diaspores.
Where is the rachis located?
The term "rachis" refers to the extension of the petiole into the leaf blade that the leaflets are attached to in a pinnate leaf palm. The leaves of pinnate leaf palms have both a petiole and a rachis. Initial symptoms normally occur on the lowest (oldest) living leaves in the canopy.
What is a rachis on a plant?
noun plural rachises, rhachises, rachides or rhachides (ˈrækɪˌdiːz, ˈreɪ-) botany the main axis or stem of an inflorescence or compound leaf. ornithol the shaft of a feather, esp the part that carries the barbs. another name for spinal column.
What is a rachis of a leaf?
Definition of rachis 1 : an axial structure: such as. a(1) : the elongated axis of an inflorescence. (2) : an extension of the petiole of a compound leaf that bears the leaflets.
What is a rachis of fern?
Rachis. The central midrib or stalk of the lamina. It is a continuation of the stipe. Often the rachis differs from the stipe, both in colour and covering of hairs and scales.
What is rachis in wheat?
The rachis is the main axis of the inflorescence, or spike, of wheat and other cereals, to which the spikelets are attached. Spikelets are small inflorescences bearing one or more florets, or small flowers, along with a set of miniature bractlike leaves.
What is the function of the rachis?
In vertebrates, rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually forms the supporting axis of the body and is then called the spine or vertebral column. Rachis can also mean the central shaft of pennaceous feathers.
What is rachis made of?
The rachis cortex is a complex hierarchical structure composed of microlayers of β-keratin, a composite material consisting of keratin fibres embedded within a viscoelastic matrix [14]. Within extant bird species, the material properties of β-keratin are poorly understood.
What is rachis Cycas?
The peculiar feature of the rachis is the arrangement of the vascular bundle i.e., in an inverted omega shape pattern. Each vascular bundle is covered by a single-layered sclerenchymatous bundle sheath. Vascular bundles are collateral, endarch and open.
What is rachis in rice?
Schematic representation of a rice panicle comprising a main central axis (blue line) named rachis, to which primary branches (Pb) are attached (black lines); the primary branches bear secondary branches (Sb, green lines), which in turn bear tertiary branches (Tb, orange lines).
Where are ferns found?
Geographically, ferns are most abundant in the tropics. Arctic and Antarctic regions possess few species. On the other hand, a small tropical country such as Costa Rica may have more than 900 species of ferns—about twice as many as are found in all of North America north of Mexico.
Where do ferns grow?
Ecologically, the ferns are most commonly plants of shaded damp forests of both temperate and tropical zones. Some fern species grow equally well on soil and upon rocks; others are confined strictly to rocky habitats, where they occur in fissures and crevices of cliff faces, boulders, and taluses.
What does rachis represent morphologically?
Answer: In pinnately compound leaf, the number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf as in neem. In case of a palmately compound leaf, the leaflets are attached at a common point, i.e., at the tip of petiole as in silk cotton.
Phenology, Development, and Growth of the Wheat (Triticum Aestivum L.) Shoot Apex: A Review
Rachis internode extension coincides with spikelet formation for spring wheat (Holmes, 1973 ). Spike growth is very slow in the early stages of development and rapid elongation starts when the flag leaf ligule is just visible ( Krumm et al., 1990 ).
Diversity in Barley
Udda Lundqvist, Jerome D. Franckowiak, in Developments in Plant Genetics and Breeding, 2003
Origin, Domestication and Diffusion of Sorghum bicolor
Kamala Venkateswaran, ... N. Sivaraj, in Breeding Sorghum for Diverse End Uses, 2019
Identification of entomopathogenic fungi
Richard A. Humber, in Manual of Techniques in Invertebrate Pathology (Second Edition), 2012
Pongamia pinnata
S.L. Badole, S.L. Bodhankar, in Bioactive Food as Dietary Interventions for Diabetes, 2013
Grapevine structure and function
The inflorescence is a complex of highly modified, reduced shoots. The rachis is the inflorescence shoot system ( Fig. 3.22 ). It is composed of a basal portion (the peduncle), two main branches—the inner and outer (or lateral) arms, and various subbranches, terminating in pedicels. Pedicels give rise to individual flowers.
Feed and industrial uses for cereals
Kurt A. Rosentrater, A.D. Evers, in Kent's Technology of Cereals (Fifth Edition), 2018
What is a rachid?
n. pl. rachises or rachides (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.
What is the most common disease in the spine?
The most common of these is pott's disease, or tuberculosis affecting the vertebrae and soft tissues of the spine. Another is osteitis deformans, a type of bone inflammation in which parts of the bone are replaced by softer tissue. scoliosis is a curvature of the spine toward one side.
Which part of the skeleton is the axis of the spine?
The spinal column is the axis of the skeleton; the skull and limbs are in a sense appendages. The vertebrae also provide the protective bony corridor ( spinal canal) through which the spinal cord passes; they can move to a certain extent and so give flexibility to the spine, allowing it to bend forward, sideways and, to a lesser extent, backward. ...
What is the spine?
spine. 1. a thornlike process or projection; called also acantha and spina. 2. the rigid bony structure in the midline of the back, composed of the vertebrae; called also backbone, spinal column, and vertebral column. The spinal column is the axis of the skeleton; the skull and limbs are in a sense appendages.
Bird Feather Anatomy
Bird feathers come in a variety of sizes, shapes, and colors. These traits reflect the various functions of bird feathers, including protection, warmth, and flight. For the bird enthusiast, feathers also serve as an important way to identify different bird species.
Parts of a Feather
Although a feather might look simple in structure to the naked eye, feathers have complex anatomies, which reflect how birds use them. All feathers consist of two main parts, the hard central shaft called the rachis and the softer side branches known as barbs.
Types of Feathers in Birds
Feathers are classified as pennaceous or plumaceous. Pennaceous feathers contain hooked barbules with hamuli and are more structured and tightly interlocked with one another. Pennaceous feathers are so stiff that they were used as writing utensils hundreds of years ago. By contrast, plumaceous feathers possess barbules lacking hamuli.
How Birds Use Their Feathers
As indicated by the different feather types described above, birds use each of these feathers for different functions. Some of these functions will be described below.
Bird Feathers: Crossword Puzzle
This activity will help you assess your knowledge of the types and parts of bird feathers.
