Glossary of Botanical Terms - I

I

illegitimate name (nomen illeg.)

a name not abiding by the rules of the botanical Codes, e.g. later homonyms, cultivars that have been Latinised after 1 Jan 1959; cultivar names with more than 10 syllables or 30 letters; cultivar names that use confusing names of other plants, e.g. Camellia 'Rose'.

imbricate

overlapping each other; of perianth parts, edges overlapping in the bud (the convoluted arrangement is a special form of imbrication).

imparipinnate

a pinnate leaf with an odd number of pinnae (terminated by a single leaflet); compare paripinnate.

in

in nomenclature, where the preceding author published the name in an article or book, authored or edited by the succeeding author.

inbreeding

the production of offspring between closely related parents leading to a high degree of similarity; self-fertilization is the most intense form of inbreeding.

incised

cut deeply and (usually) unevenly (a condition intermediate between toothed and lobed).

included

enclosed, not protruding; for example stamens within the corolla.

incurved

bent or curved inwards; of leaf margins, when curved towards the adaxial side.

ined.

abbreviation of Latin inedita, an unpublished work. Used to indicate that a botanical name appeared only in a manuscript that was not published, so the name is invalid.

indefinite

variable in number; numerous; e.g. more than twice as many stamens as petals or sepals, or when an inflorescence is not terminated by a flower (and continues growing); cf. definite.

indehiscent

not opening in any definite manner at maturity; usually referring to fruit.

indeterminate

unlimited, usually in growth.

indigenous

native to the area, not introduced, and not necessarily confined to the region discussed or present throughout it (hardly distinct from ‘native’ but usually applied to a smaller area). For example, the Cootamundra Wattle is native to Australia but indigenous to the Cootamundra region of southern New South Wales; cf. endemic.

indumentum

any surface covering, e.g. hairs, scales; a collective term for such coverings.

indusium

1. a membrane covering the sporangia of some ferns.

2. a cup enclosing the stigma in Goodeniaceae.

inferior

of an ovary, at least partly below the level of attachment of other floral parts; compare superior.

inflated

swollen, like a bladder.

inflexed

bent sharply upwards or forwards; compare deflexed.

inflorescence

several flowers closely grouped together to form an efficient structured unit; the grouping or arrangement of flowers on a plant.

infraspecific

denotes taxonomic ranks below species level, for example subspecies.

infructescence

the grouping or arrangement of fruits on a plant.

infundibular (infundibularform)

funnel-shaped, for example in the corolla of a flower..

inrolled

rolled inwards.

insectivorous

catching, and drawing nutriment from, insects.

integument

in general, any covering, but especially the covering of an ovule.

interjugary glands

in pinnate leaves, glands occurring along the leaf rachis between the pinnae (occurring below the single, and often slightly larger, gland at or just below the insertion of the pinnae); cf. jugary.

internode

the portion of a stem between two nodes.

interpetiolar

of stipules, between the petioles of opposite leaves.

intramarginal

inside but close to the margin, for example a vein in a leaf.

intrastaminal

inside the stamens or androecium, usually referring to the location of a nectary disk.

introrse

of anther locules, with opening towards the centre of flower (at least in bud); cf. extrorse, latrorse.

invalid

use of names not validly published according to the Code; i.e. they are not strictly 'names' in the sense of the International Code of Botanical Nomenclature.

involucre

a group of bracts surrounding the base of a flowerhead; e.g. as seen in a daisy.

involute

rolled inwards, for example when the margins of a leaf are rolled towards the adaxial (usually upper) surface; compare revolute.

irregular

cannot be divided into two equal halves through any vertical plane; compare zygomorphic, actinomorphic, regular.

isobifacial

(of flat structures, especially leaves) with both surfaces similar, usually referring to cell types or to the number and distribution of stomata.