Botany 101 terms

beginner botany terms

Cell

Membrane-bound protoplasmic mass. The unit of plants that make up tissues.

Cellulose

a highly insoluble compound; component of plant cell walls conferring a rigid structure to the plant.

Organelles

where functions are carried out inside the cells. Examples are nucleus, mitochondria, and chloroplasts.

Tissue

a group of similar cells that perform a particular function

Node

point at which the leaf leaves the stem

Internode

the length of the stem between two nodes

Petiole

leaf stem

Meristems

tissues in which cells are actively dividing, resulting in growth of the plant.
apical meristems are located at the tips of roots and shoots.

Shoot apical meristems

responsible for new leaves, branches, and flowers.

Axillary buds

these buds are apical meristems that will become new shoots. If the terminal meristem is removed, auxiliary buds are encouraged to grow. (i.e. pruning for lateral growth)

Roots

the underground parts of the plant that serve to anchor the plant, absorb nutrients and water, store food, and support the system.

Taproots

have branching side roots and a main root to access sources of water

Fibrous roots

have no main stem, but many branches.

Root anatomy

Aerial roots

arise from the stem and take water from the air

Parasitic roots

penetrate other plants for their nutrients and water

Stems

support the leaves, reproductive structures, and fruit. They contain the vascular system that transports water and food throughout the entire plant. Stems position leaves to receive light for photosynthesis.

Xylem

conducts water and minerals. Absorbed by the root and distributed upward to every part of the plant.

Phloem

conducts sugars manufactured in the leaves by photosynthesis. These materials are transported down throughout the plant.

Stolons

horizontal, above ground stems

Rhizomes

underground horizontal stems

Crowns

have leaves and flowers on a stem that has very short internodes

Tubers

underground stems that store starch.

Corms

look like bulbs but are actually stem tissue (bulbs are primarily leaf tissue)

Vascular Cambium

secondary growth in woody plants increases the diameter of the stem due to lateral or secondary meristems. The vascular cambium produces phloem, or inner bark, to the outside of the cambium and xylem (wood) to the inside.

Heartwood

older wood in the venter [of a tree] that becomes nonfunctional

Sapwood

Xylem produced in previous years that may still be active in the transport of water and nutrients.

Photosynthesis

the production of plant food in the leaf by access to sunlight and water

sessile leaf

no petiole.

stipule

leaf found where the petiole contacts the stem

palmately veined leaf

dichotomous leaf

pinnately veined leaf

parallel veined leaf

Stomata

pores, mostly on the underside of the leaf, allowing exchange of gas (CO2 and H2O)

Spine leaf

modified leaves that discourage nibbling from animals

Tendrils

leaves that are adapted to attach to a supporting structure

Bracts

modified leaves at the base of a flower.

Needles (leaves)

modified leaf adapted for dry wind and cold weather. They have a thick outer coat, little surface area, recessed stomata, and specialized cells protecting the vascular system. The needles contain resins.

Bud

underdeveloped shoot from which embryonic leaves or flower parts arise. A tough outer coat protects the bud from insects and the environment.

Angiosperms

flowering plants with seeds enclosed in fruits

Gymnosperms

non-flowering plants

flower anatomy

Stamen

Male flower part. consists of an anther (which holds the pollen) and the filament (the stalk that holds the anther position for access by the pollinator).

Carpel

Female flower part. Consists of the stigma (a sticky structure which receives the pollen), the style (which holds the stigma in position) and the ovary. Several carpels may be fused into a pistal.

Flower Symmetry

Radial (many planes of symmetry)
Bilateral (one plane of symmetry)

Position of ovary

Superior (petals attached to bottom of ovary)
Semi-superior (petals attach in middle of ovary)
Inferior (petals attach at top of ovary)

Inflorescence

arrangement of flowers on a stem

Conifer

cone bearing. Most conifers have soft wood. Stem becomes axis of cone. Leaves are modified into scales. In female cones: auxiliary bud becomes ovule and seed sits on woody scale with no protection. Male and female cones usually on same tree I different spaces. Pollen arrives by wind or insects.

Anatomy of seeds

Seed coat protects embryo from weather and dehydration. Endosperm provides food to give embryo a start. May have one (monocotyledons) or two (dicotyledon) leaves.

Pericarp

ovary wall. 3 layers: exocarp (outer layer), mesh carp and endocarp).

Pollination

Come back to later

Plant Growth Patterns

Woody vs Herbaceous.
Deciduous vs Evergreen.
Monocots vs Dicots

Woody plants

has lateral meristem causing plant to frown in thickness and strength. This secondary growth is characteristic of woody trees, shrubs, and vines. Woody plants are deciduous or evergreens.

Herbaceous plants

lack secondary growth and tend to die back in the winter

Deciduous plants

lose their leaves or needles in winter

Evergreen plants

have either leaves and needles. The plants lose and replace some leaves or needles every year.

Monocots (monocotyledons)

leaves are narrow and parallel veined, flower parts are in threes, stems have vascular bundles scattered throughout, there is generally no secondary (woody) growth, one leaf emerges from seed.

Dicots (dicotyledon)

leaves are wide and net veined, flower parts are not usually in multiples of three, vascular bundles in the stem are arranged in a ring, there may be secondary growth, two leaves emerge from seed

Annuals

live for only one growing season. They flower, set seed and die.

Biennial

lives for two growing seasons. In the first year they produce leaves, roots, and compact stems. Flowers are produced and seeds developed in the second year.

Perennials

Survives for many growing seasons. Survives winter and returns in spring.

USDA Zones

Classification of plants according to hardiness (lowest temperature the plant will likely withstand). Maryland is in zone 6a to 7b.

Latin binomials

Genus species. italicized. genus capitalized.

Classification system:

Kingdom
Phylum
Class
Order
Family
Genus
Species

Arrangement of leaf on stem

Alternate
Opposite
Whorled

Alternate leaf

one leaf at a node

Opposite leaves

two leaves per node

Whorled leaf

three or more leaves per node

Leaf shape

Aid in identification. Major shapes are lanceolate, cordate, linear, elliptical, and ovate.

Linear leaf

Oval leaf

Oblong leaf

Ovate leaf

Obovate leaf

Deltoid leaf

Cordate leaf

Lanceolate leaf

Elliptical leaf

Leaf Margins

the edge of the leaf, can take many forms such as entire, undulate, serrate, double serrate, crenate, and lobed.

entire leaf

straight edge

undulate leaf

wavy

serrate leaf

toothed

double serrate leaf

toothed x2

crenate leaf

rounded teeth

lobed leaf

rounded extension

Simple leaf

one blade attached to stem

Compound leaf

the leaf is divided into leaflets. If leaflets further divided, it is said to be double compound. To determine what kind of leaf you have, look for auxiliary bud. Leaves have one, leaflets will not.

Leaf tips

i.e.. acute, acuminate, bristle-tipped, truncate and obtuse.

Acute leaf tip

pointed tip

acuminate leaf tip

a long narrow pointed tip

bristle tip leaf

truncate leaf tip

squared tip

obtuse leaf tip

rounded tip

Photosynthesis reaction

6CO + 6H20 \= C6H12O6 + 6O2

Respiration

the break down and utilization of food by the plant. Sugars and oxygen are broken down into carbon dioxide, water, and energy.

Transpiration

Water vapor evaporated from the stomata. This pulls water and minerals up through the xylem from the roots. It also cools off the leaves.

Hormones

a substance that is produced in one place and acts at another. The major plant hormones are auxins, gibberellins, cytokinins, ethylene, and abscisic acid.

Auxins

a group of hormones that stimulate cell growth and direct the development of lateral meristems. Also promote growth of lateral and adventitious roots. They are produced at meristems in terminal buds.

Cytokinins

promote cell division and differentiation. They are synthesized in the roots and enhance axillary bud growth. This counteracts the effects of auxins in apical dominance. Cytokinins also delay the aging of leaves.