IAPT n. Acronym. International Association for Plant Taxonomy, a group of those who are interested in botanical systematics sensu lato, and established to encourage research as well as to publish contributions in various projects, including those published in their journal Taxon.

IBC n. Acronym. International Botanical Congress, an international meeting between botanists, mycologists, and phycologists, now held every six years, as a means of standardising the ICN, as well as providing for presentation of new research.

ICN n. Acronym. International Code of Nomenclature for algæ, fungi, and plants; since the Melbourne IBC in July 2011, the accepted acronym for the taxonomic guidelines followed in naming of plants, fungi, algæ, as well as anamorphs, teleomorphs, and fossils of these.

il·li·xa (il lik´sa) n. in the novel The Lions of Al-Rassan, by Guy Gavriel Kay, a plant bearing white flowers which, when fed upon by a beetle, produce a crimson dye. It grows south of the city of Cartada. [Asharic]

im·park (im pärk´) v.t. enclose or define (land) to protect it as a park. [ME < OF emparquer < em- within + parc park] —im´par·ka´tion, n.

in·cu·bous (in´kyə bəs) adj. of a leafy liverwort, bearing microphylls inserted upon the stem in such a manner that their apex covers the proximal end of the next superior microphyll. [NL < L incubare lie upon + OF -ous full of]

Index Herbariorum n. a publication naming all large public herbaria, their location, web address, contents, history, staff information, and their unique 4-8 letter acronym. Originally published by the IAPT, the database is now maintained by the New York Botanical Garden.

Index Nominum Genericorum n. ING.

Indian grass n. a grass native to the Americas (Sorghastrum nutans (L.) Nash, of the Poaceae), growing in prairie and savanna habitats, and reaching nearly 2m in height.

in·du·si·um (in dü´zē əm) n. -si·a. in botany and mycology, any of several unrelated thin tissue structures which have a skirtlike or netlike appearance, such as the structure which covers the sori of certain fern fronds. [NL < L indusium tunic] —in·du´si·al, adj.

in·fra·fi·lo·sum (in´frə fī´lō´süm) n. -sa. in ferns of suborder Hydropteridineae Rothwell & Stockey, a distinct layer to the outer megaspore exoperine, consisting of abundant fine hairs which are generated upon the surface of the megaspore itself. [< L infra beneath + filum thread + -ōsum augmented, prone to]

in·fra·spore (in´frə spôr´) n. in ferns of suborder Hydropteridineae Rothwell & Stockey, that portion of the megaspore which constitutes the actual cell body of the spore. [NL < L infra beneath + Gk. spora σπορά seed]

ING n. Acronym. Index Nominum Genericorum, a compilation of all known names of genera which have been published, maintained by the Smithsonian National Museum of Natural History. [< L index nominum genericorum index of generic names]

International Association for Plant Taxonomy n. IAPT.

International Code of Nomenclature for algæ, fungi, and plants n. ICN.

International Plant Names Index n. IPNI.

interpetiolar stipule n. on opposite leaves, a conjoining of adjacent stipules so that they appear as a single small distinct leaf.

in·tro·gress (in´trō gres´) v.i. in hybridisation, of a range of features from one parent species which become expressed to a greater or lesser extent in successive generations of progeny. [on the pattern of egress] —in´tro·gressed´, adj.

in·tro·gres·sion (in´trō gresh´ən) n. in hybridity, the transfer of genetic information from one species to another, followed by repeated backcrossing. A hybrid swarm often results. [< L introgredī step in < intro- to the inside + gradi proceed, walk] —in´tro·gres´sive, adj. —in´tro·gres´sive·ly, adv.

in·tus·sus·cep·tion (in´tə sə sep´shən) n. 1 growth of a cell by means of deposition of additional wall material around existing cell wall components; apposition. 2 assimilation of new substances into the existing components of living tissue. [< F < NL intussusceptio < L intus within + susceptio (< suscipere take up)] —in´tus·sus·cep´tive, adj.

in·vag·i·nate (in vaj´ə nāt´) v.i. of a tissue, be turned back upon itself in folds. —adj. turned back upon itself, bearing many folds.

in·vag·i·na·tion (in vaj´ə nā´shən) n. the space separating two single layers of infolded tissue. [< L in- in, into, within + vagina sheath + -ationem state or condition]

in·va·sive (in vā´siv) adj. n. —adj. of species, those which are non-indigenous to a habitat or terrain in which they have begun to appear and spread prolifically, either through spreading from adjacent natural habitats or by spreading from accidental or intentional plantings. —n. a species, or an individual of this species, which is non-indigenous to a habitat or terrain. [ME < Med.L invāsīvus tending to invade] —in·va´sive·ly, adv.

ip·e·cac·u·an·ha (ip´i kak ü än´ya) or ip·e·cac (ip´i kak) n. 1 a low South American shrub (Carapichea ipecacuanha (Brot.) L.Andersson, of the Rubiaceae), which has long been used as an emetic, and for several other medicinal uses. 2 the dried rhizome and roots of this plant, source of the active alkaloids. [< Pg. < Tupi ipekaaguéne emetic creeper < ipe small + kaa leaves, herb + guéne vomit]

IPNI n. Acronym. International Plant Names Index, an internet database compiled to present the Index Kewensis in a manner convenient for users of the internet. It documents known published names for vascular plants, as well as their authorities and location of publication, and is managed from Kew Gardens.

Irish heath n. either of the species of the genus Daboecia D.Don (especially D. cantabrica (Huds.) K.Koch, of the Ericaceae), which are upright heaths growing on cliffs and rocks in coastal Ireland, France, Iberia, and the Azores; saint Dabeoc’s heath.

Ir·men·sä·u·le (ēɾ´mən se´ü le) n. a particular Irminsul, a colossal tree trunk near the Weser River in Lower Saxony, surrounded by a sacred wood, present up to the year 772AD when it was burned and destroyed by Charlemagne during his conquest of Saxony. It was regarded as a pillar of heaven. [Saxon]

ir·ri·gate (ēr´i gāt) v.t. 1 supply water to crops or other cultivated plants in the field or in an artificial habitat. 2 in certain laboratory processes, apply a steady stream of water to a tissue sample. [< L irrigātus wetted, watered] —ir´ri·ga·ble, adj. —ir´ri·ga´tion, n.

isle of ebony n. 1 in the Arabian Nights, the island country of Madagascar – perhaps an original source for this type of wood. 2 a prominent upland in England near Tenterden, Kent, surrounded until the 1600s by the Rother River, and until then a market centre.

i·so·lat·er·al (ī´sō lat´ər əl) adj. of a leaf, having stomata on both (or all) faces. [NL < Gk. isos ἶσος equal, similar + lateris λατερις the side, flank + L -alis pertaining to]

i·so·me·gueth (ī´sō me geth´ or ī´sō mə geth) adj. of paired or numerous similar structures, being all of a similar size, or a similar size to their counterpart. [< F < Gk. isos ἶσος equal, similar + megas μέγᾶς great + ethos ἔθος character, habit]

i·so·spo·ry (īs´ə spôr´ē) n. of the sexual expression of a plant, the case in which the gametophytes are produced by spores which do not differ in size or appearance, and which are produced in the same sporangium. [< Gk. isos ἶσος equal + spora σπορά a seed + E -y partaking of the nature of] —i´so·spore, n.

I·ðunn (i ŦHün´) n. a goddess of the Nordic pantheon, who carries the apples of eternal youth. She is represented as either one of the goddesses or descended from elves. Additionally, she is reported to have been turned into a nut, when rescued by Loki (after having been put at hazard by this trickster in the first place).

i·vy (ī´vē) n. -vies. 1 any of several Eurasian evergreen woody climbers of the genus Hedera L. (of the Araliaceae), usually bearing palmately 5-lobed leaves. 2 any of several plants which roughly approximate this growth form, as – for example – poison ivy. [< OE īfig < Gmc.]

Ivy League n. a group of universities and colleges all located in the northeastern US, and all noted for high scholastic achievement and for bestowing social prestige. They comprise Yale, Harvard, Princeton, Brown, Columbia, Dartmouth, Cornell, and University of Pennsylvania.