Plant Anatomy - Tissue and Tissue System

A set of vocabulary flashcards covering the key concepts of plant anatomy, tissue types, and the histological structure of plant systems based on the lecture notes.

Plant Anatomy

The study of internal structure and organisation of plants, derived from the Greek words Ana (as under) and temnein (to cut).

Nehemiah Grew

Known as the Father of Plant Anatomy, lived from $1641$ to $1712$.

Katherine Esau

A pioneering researcher and author of the book Anatomy of Seed Plants, awarded the National Medal of Science by the USA in $1989$.

Tissue

A group of cells that are alike in origin, structure, and function.

Histology

The study of tissues.

Meristem

A term coined by C. Nageli in $1858$, referring to actively dividing cells that are self-perpetuating.

Apical meristem

Located in the apices of roots and shoots, responsible for primary growth and increasing the length of the plant.

Intercalary meristem

Tissues occurring between permanent tissues responsible for the elongation of internodes.

Lateral meristem

Tissues occurring along the longitudinal axis of stem and root responsible for secondary thickening, such as vascular cambium and cork cambium.

Protoderm

The meristematic tissue that gives rise to the epidermal tissue system, including epidermis, stomata, and hairs.

Procambium

The meristematic tissue that gives rise to primary vascular tissues like xylem and phloem.

Mass meristem

A meristem that divides in all planes, with examples including endosperm, young embryo, and sporangium.

Dermatogen

The outermost layer of the shoot apex in Histogen theory that gives rise to the epidermis.

Plerome

The innermost layer in Histogen theory which gives rise to the stele.

Calyptrogen

The histogen in the root apical meristem that gives rise to the root cap.

Quiescent Centre Concept

Proposed by Clowes ($1961$), this is an apparently inactive region of cells in the root promeristem that acts as a site for hormone synthesis.

Parenchyma

A living ground tissue made of thin-walled cellulose cells used for storage and packing.

Idioblasts

Parenchyma cells that store resin, tannins, or crystals of calcium carbonate and calcium oxalate.

Aerenchyma

Parenchyma containing air in its intercellular spaces, providing buoyancy and aeration for plants like Nymphae and Hydrilla.

Chlorenchyma

Parenchyma cells containing chloroplasts, specialized for photosynthesis, found in the mesophyll of leaves.

Collenchyma

A simple, living mechanical tissue with cell walls unevenly thickened by hemicellulose and pectin, common in the hypodermis of dicot stems.

Sclerenchyma

Dead cells with uniformly thickened, lignified secondary walls, lacking protoplasm at maturity.

Brachysclereids

Also known as stone cells; isodiametric sclereids with hard walls found in contexts like the pulp of Pyrus (pear).

Trichosclereids

Hair-like thin-walled sclereids found in stems and leaves of hydrophytes, often with small angular crystals embedded in the wall.

Ramie fibre

Fibres from Boehmeria which are the longest plant cells at $55\,cm$ long.

Xylem

The principal water-conducting tissue in vascular plants, a term introduced by Nageli in $1858$.

Exarch

A condition common in roots where the protoxylem lies towards the periphery and the metaxylem lies towards the centre.

Endarch

A condition seen in stems where the protoxylem lies towards the centre and the metaxylem towards the periphery.

Tracheids

Dead, lignified, elongated cells with tapering ends that are the chief water-conducting elements in Gymnosperms and Pteridophytes.

Vessels

Long tube-like structures formed from vessel elements joined end to end, perforated at the end walls, and serving as chief water conductors in Angiosperms.

Syncyte

A cell formed by the fusion of cells, such as dead vessels or living sieve tubes.

Phloem

The food-conducting complex tissue of vascular plants, coined by C. Nageli in $1858$.

Sieve Tubes

Long, tube-like conducting elements in Angiosperms formed from sieve tube elements with end walls called sieve plates.

P-Protein

Also known as slime body, a special protein found in mature sieve tubes.

Companion Cells

Specialized parenchyma cells connected to sieve tubes via pits, serving to maintain pressure gradients in Angiosperms.

Callose

A substance that forms plugs to block the pores in mature sieve plates.