Plant Cells and Tissues (Primary Growth)

Apical Meristems

Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in height

Lateral Meristems

A meristem that thickens the roots and shoots of woody plants.

Intercalary Meristems

Found in monocots, actively produce new cells for increases in length, responsible for grass regrowing

Protoderm

The outermost primary meristem, which gives rise to the epidermis of roots and shoots.

Ground meristem

gives rise to the ground tissue system (pith and cortex)

Provascular tissues

develops into primary vascular tissues

Parenchyma

Fundamental tissue composed of thin-walled living cells that function in photosynthesis and storage.

Collenchyma

A flexible plant cell type that occurs in strands or cylinders that support young parts of the plant without restraining growth

Sclerenchyma

type of ground-tissue cell with an extremely thick, rigid cell wall that makes ground tissue tough and strong; dead at maturity

Glandular cells

secrete Nectar; Fragrances; Mucilage; Resins; Oils

Transfer cells

Parenchyma cells that mediate short-distance transport of material; They have a large, extensive plasma membrane with numerous molecular pumps due to wall ingrowths

Phloem

Parenchyma tissue that conducts nutrients over long distances

Chlorenchyma

Parenchyma cells containing chloroplasts that function in photosynthesis

Mechanical and conductive

Two types of sclerenchyma

Fibers

Long and flexible mechanical sclerenchyma

Sclereids

A short, irregular sclerenchyma cell in nutshells and seed coats and scattered through the parenchyma of some plants.

Pit-pairs

a set of aligned pits in adjacent sclerenchyma cells

Node

where the leaf attaches to the stem

Internode

region between nodes

Leaf scar

a scar marking the former point of attachment of a leaf or petiole to the stem

Lenticels

Small raised areas in the bark of stems and roots that enable gas exchange between living cells and the outside air.

Axillary bud

a bud that grows from the axil of a leaf and may develop into a branch or flower cluster.

Terminal bud

bud at tip of a stem responsible for terminal growth

Bud scale

a modified leaf that forms a protective covering for a bud until it opens

Phyllotaxy

arrangement of leaves on a stem

Alternate phyllotaxy

one leaf per node

Opposite phyllotaxy

two leaves per node

Whorled phyllotaxy

more than two leaves per node

Distichous phyllotaxy

leaves arranged in two rows when viewed from above

Decussate phyllotaxy

leaves arranged in four rows when viewed from above

Spiral phyllotaxy

each leaf is located slightly to the side of the ones immediately above and below it, and leaves form a spiral up the stem.

Rhizomes

horizontal underground stems

Tubers

the thick, fleshy parts of underground stems functioning as storage

stolons/runners

horizontal above ground stems

tendrils

a slender threadlike appendage of a climbing plant, often growing in a spiral form, that stretches out and twines around any suitable support.

Cladophyll

a flattened stem resembling and functioning as a leaf

Epidermis

outer layer of a herbaceous stem

Cutin

makes up cuticle

Cuticle

The waxy, waterproof layer that covers the leaves and stems of most plants.

Guard cells

control the opening and closing of stomata

Trichomes

tiny hair structures on leaves; help reduce the evaporation of water from the plant.

Stomata

the small openings on the undersides of most leaves through which oxygen and carbon dioxide can move

cortex

Ground tissue in a stem or root between the bark and the vascular tissue

pith

ground tissue internal to the vascular tissue

xylem

Nonliving vascular tissue that carries water and dissolved minerals from the roots of a plant to its leaves

ring

arrangement of vascular bundles in eudicots

scattered

arrangement of vascular bundles in monocots

Primary growth

Growth produced by apical meristems, which lengthen stems and roots.

Secondary growth

Growth produced by lateral meristems, which thickens the roots and shoots of woody plants (found only on eudicots)

leaf primordia

Tiny embryonic leaves that develop into mature leaves

subapical meristem

Produces new cells in the region a few micrometers behind an active shoot or apical meristem