Glossary of botanical terms

achene
A dry indehiscent fruit.

actinomorphic
Radially symmetrical, like a dandelion or a daisy.

alternate
attached along an axis alternately, rather than in opposite pairs or in whorls of several.

ament
A catkin.

bract

bundle scar
The scar formed by the vascular bundles ("veins") on the leaf scar.

catkin

compound leaf
A leaf that is composed of separate leaflets, instead of having a single surface in one piece. It has a central stem if it is pinnately compound, called the rachis, off which leaflets grow. If the leaf is palmately compound, all of the leaflets radiate from a common point somewhat like the outstretched fingers of the human hand.

cordate
heart-shaped; also, shaped like the top of a heart with two lobes.

corymb

cotyledon
One of the usually two leaves that first sprout when a seed germinates. They are not shaped like the true leaves that grow later.

d.b.h.
Diameter breast high.

deciduous
Shed, falling.

dioecious
Having male and female flowers on separate plants.

drupe
A fruit with an outer skin, a fleshy layer, and an innermost hard bony or stony layer ("pit") which encloses the seed. The fruits of the genus Prunus (cherries, peaches, plums) are drupes.

gland

inflorescence
The unit in which flowers grow. A lilac flower is about half an inch across with four tiny petals. The thing you wrench off the plant and stick in a vase is the inflorescence.

leaf scar
The mark or scar left on a twig by the base of a petiole after the leaf falls.

leaflet
A compound leaf is divided into leaflets.

lenticel
One of many naturally produced corky, blistery areas on tree bark usually line-shaped.

liana
A woody climbing vine.

monoecious
Having male and female flowers on different plants. Opposed to dioecious, with male and female flowers on same plant. Neither term applies to plants with perfect flowers.

opposite
attached along an axis in pairs, each member of the pair opposite the other. See example.

palmate.
Radiating out from a common point at angles to eachother, somewhat like fingers on a hand. Opposed to pinnate, where the alignment is like the barbs on a feather, in two opposite parallel rows. See example.

peduncle.
The stem of a flower or fruit.

perfect
Of a flower containing male and female parts, hermaphroditic.

petiole.
The stem of a leaf. Its absence makes the leaf sessile. The stem of a flower or fruit (the same thing since flowers turn into fruits) is a peduncle.

petiolule
The stem of a leaflet.

pinnate.
Spreading out on the two sides of an axis like the barbs of a feather, or the leaflets of trees like the walnut.

prickle

raceme

rachis

samara.
A dry fruit, like an achene, but equipped with a wing or wings.

schizocharp
A fruit that splits into parts when ripe, such as the maple's, which breaks in two.

sepal

serrate
Of teeth or having teeth like a saw's (regular and somewhat pointed towards the tip of the leaf).

sessile
Lacking a stem (petiole, peduncle, &c), attached directly.

sinus
In the margin of a leaf, a concave, scooped out area.

spine
A spine is pointy like prickles and thorns, but unlike them is a modified leaf or stipule. The structures on Black Locust (Robinia) are spines.

spur shoot

stigma
The organ atop the pistil which receives the pollen.

stipulate

stipule

thorn
Thorns are modified twigs, and hence woody and present on twigs, branches or trunk. Hawthorns (Crataegus) and Honey Locust (Gleditsia) have thorns. Compare to Prickle and Spine.

umbel

zygomorphic
Bilaterally symmetrical, with a plane of symmetry dividing it into to halves which are mirror images. Eg., the flowers of orchids, or the human body, or a bed.

Copyright © 1997, 2012 by Brian Laurence Hughes
The URL of this page is http://blh23.net/trees/glossary.php
Last updated September 4, 2012.