Glossary of Botanical Terms - H

H

habit

the general external appearance of a plant, including size, shape, texture and orientation.

habitat

the place where a plant lives; the environmental conditions of its home.

hair

a single elongated cell or row of cells borne on the surface of an organ.

half-inferior

of ovary, partly below and partly above the level of attachment of the other floral parts; compare inferior, superior.

halophyte

a plant adapted to living in highly saline habitats; a plant that accumulates high concentrations of salt in its tissues.

hand-pollination

the controlled act of pollination that excludes the possibility of open-pollination.

haploid

of chromosomes, and relative to the phase of an alternation of generations in which the duplicated chromosome set or diploid condition is reduced; the condition when the chromosomes are not duplicated, e.g. the complement of chromosomes in the nucleus of a gamete; a single basic set of chromosomes in the nucleus of a cell. This may be expressed symbolically as n, where n = the gamete number of chromosomes.

hastate

like the head of a halbert, i.e. narrow and pointed but abruptly enlarged at the base into two acute diverging lobes; may refer only to the base of a leaf with such lobes; cf. sagittate.

haustorium

in parasitic plants, a structure developed for penetrating the host's tissues.

head

see capitulum.

heathland

vegetation dominated by small shrubs which usually have ericoid leaves.

helicoid

coiled; of a cymose inflorescence, when the branching is repeatedly on the same side (the apex is often recurved); cf. scorpioid.

herb

a vascular plant that does not develop a woody stem; e.g. a violet.

herbaceous

not woody; usually green, and soft in texture.

herbarium

a collection of preserved, usually dried, plant material. Also a building in which such collections are stored.

hermaphrodite

see bisexual.

heteromorphic

of 2 or more distinct morphologies (e.g. of different size and shape).

hilum

the scar on a seed coat where it separates from its stalk (funicle).

hip

the fruit of a rose.

hippocrepiform

horseshoe-shaped.

hirsute

bearing coarse, rough, longish hairs. See Indumentum.

hispid

having long erect rigid hairs or bristles, harsh to touch.

hoary

covered with a greyish to whitish layer of very short, closely interwoven hairs, giving a frosted appearance.

holotype

a type chosen by the author of a name; cf. a lectotype, which is chosen by a later author.

hort.

(never capiltalised) of gardens, an author citation used in two ways:

as a name misapplied by gardeners

2. as an invalid name derived from horticultural writings of confused authorship.

hyaline

translucent; usually delicately membranous and colourless.

hybrid

a plant produced by the crossing of parents belonging to two different named groups, e.g. genera, species, varieties, subspecies, forma and so on; i.e. the progeny resulting within and between two different plants. An F1 hybrid is the primary product of such a cross. An F2 hybrid is a plant arising from a cross between two F1 hybrids (or from the self-pollination of an F1 hybrid).

hybrid formula

the names of the parents of a hybrid joined by a multiplication sign, e.g. Cytisus ardonoi × C. purgans.

Hydrophily

a fairly uncommon form of pollination whereby pollen is distributed by the flow of waters.

hypanthium

see floral tube.

hypogynous

borne below the ovary; used to describe floral parts inserted below the ovary's level of insertion; cf. epigynous, perigynous.

hypocotyl

of an embryo or seedling, the part of the plant axis below the cotyledon and node, but above the root. It marks the transition from root to stem development.

hypocarpium

an enlarged fleshy structure that forms below the fruit, from the receptacle or hypanthium.