What is rachis What does it represent?

What is rachis What does it represent?

In zoology and microbiology 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.

Is petiole and rachis the same?

The term “petiole” refers to the portion of the leaf between the leaf base and the leaf blade. 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.

What is a Petiolule?

: a stalk of a leaflet of a compound leaf.

What do you mean by leaflet?

1 : a printed and often folded sheet of paper that is usually given to people at no cost an advertising leaflet. 2 : one of the divisions of a leaf which is made up of two or more smaller parts. 3 : a young or small leaf.

What is rachis in feather?

In feather. …of a central shaft (rachis), with serial paired branches (barbs) forming a flattened, usually curved surface—the vane. The barbs possess further branches —the barbules—and the barbules of adjacent barbs are attached to one another by hooks, stiffening the vane.

Is rachis present in Palmately compound leaf?

The rachis is the main axis or midrib which is found in the pinnately compound leaf. It is absent in truly palmately compound leaf. However, rachis is present in the costapalmate leaf which is the intermediate of pinnate and palmate leaf i.e the leaf is partially pinnate and partially palmate.

What is the meaning of axillary bud?

An axillary bud, the precursor of a branch or lateral shoot, is formed at the junction between a leaf and the stem. The shoot apex tends to inhibit outgrowth of axillary buds, a phenomenon called apical dominance. Removal of the shoot tip leads to growth of these buds to produce lateral shoots.

What is the meaning of the word rachises?

n, pl rachises, rhachises, rachides or rhachides (ˈrækɪˌdiːz; ˈreɪ-) 1. (Botany) botany the main axis or stem of an inflorescence or compound leaf 2.

Which is the best definition of a Rachi?

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.

What is the meaning of the word rachial?

noun, plural ra·chis·es, rach·i·des [rak-i-deez, rey-ki-] /ˈræk ɪˌdiz, ˈreɪ kɪ-/. Botany. the axis of an inflorescence when somewhat elongated, as in a raceme. (in a pinnately compound leaf or frond) the prolongation of the petiole along which the leaflets are disposed. any of various axial structures.

What kind of flowers does a rachis have?

Rachises are scaly, papillate, with occasional aerophores in the base of pinnae. Pistillate inflorescences are smaller and more contracted than staminate ones, and the rachises are very compact and covered by 30-50 flowers.