GLOSSARY OF BOTANICAL TERMS 



17 



Hirtellous: Minutely hirsute. 



Hispid: Bristly; beset with stiff, rough, 

 bristlelike hairs. 



Hispidulous: Minutely hispid. 



Histology: Microscopic anatomy; the 

 science or study, by the use of a 

 microscope, of the more minute 

 structures of plants and animals. 



Holotype: The sole specimen on which 

 a species is based, when that speci- 

 men was: (1) The only one ob- 

 served by the author of the species 

 at the time he prepared the original 

 description of the species; (2) the 

 one definitely and exclusively cho- 

 sen or indicated by the author as 

 the type of the species; and (3) the 

 one which alone has served to es- 

 tablish an original description (pro- 

 tograph) given or cited. 



Homonym: The same name for a dif- 

 ferent plant ; a specific or generic 

 name untenable because preoccupied. 

 For example, the generic name Pinus 

 would be a homonym, and unten- 

 able, if applicable to any other group 

 of plants than the pines. 



Hortus siccus : A herbarium ; literally, 

 a dry garden. 



Host: The organism from which a 

 parasite derives its sustenance. 

 Thus, clover is a frequent host for 

 dodder. 



Hyaline: Thin and translucent. 



Hybrid: The progeny of a male of one 

 race, variety, subspecies, species, or 

 sometimes genus, and a female of an- 

 other. In general hybridization is 

 confined to congeners unless a nar- 

 row generic concept is held. Many 

 authorities prefer to limit the term 

 hybrid to a cross between different 

 species, crosses between races being 

 termed half-breeds, while those be- 

 tween subspecies, varieties, and 

 forms, and sometimes between races 

 also, are known as crossbreeds. 

 Where the ancestry is mixed the 

 term mongrel is often applied. Hy- 

 bridization is usually indicated by 

 the cross mark ( X ) . 



Hydrophyte: A plant that grows in 

 water or in wet or saturated soils, 

 as distinguished from its opposite, 

 xerophyte, and the intermediate 

 mesophyte. 



Hypanthium: The base of a flower; 

 specifically, an enlargement or elon- 

 gation of the floral axis below the 

 calyx, commonly inclosing the ovary 

 and pistils. An apple or rose haw 

 is an enlarged, fleshy hypanthium. 



Hypha (pi. -w) : A threadlike compo- 

 nent of a fungus mycelium, length- 

 ening by growth from the tip and 

 41723°— 31 3 



often showing transverse partitions. 

 See mycelium. 



Hypogynous: Said of stamens or other 

 floral parts that are borne at the 

 base of the ovary or below it. 



Hyponym: An improperly published 

 botanical name (such, for example, 

 as a nomen nudum, or mere name, 

 without any description or figure) 

 and which, because of its indefi- 

 niteness and uncertainty, can have 

 no validity or standing under the 

 codes. For example, Aragallus is an 

 older name than Oxytropis but is. 

 rejected as a hyponym. 



I. e.: That is (Latin, id est). 



Imbricate(d) : Partially overlapping 

 like shingles or tiles on a roof as, for 

 example, the involucral bracts (phyl- 

 laries) of a thistle. (Fig. 36, B, a.) 



Immersed: A term used for aquatic 

 plants or their parts that are en- 

 tirely submerged. 



Imperfect: Wanting either stamens or 

 pistils; unisexual. Said of flowers. 



Incised: Having the margins cut into 

 sharp, deep, irregular incisions or 

 teeth. (Fig. 30, F.) 



Included: Inclosed in and not protrud- 

 ing from the surrounding organs. 

 For example, the stamens and style 

 of most bluebell {Mertensia, spp.) 

 blossoms are included. 



Indehiscent: Not spontaneously split- 

 ting open or dehiscing. 



Indeterminate: The (more usual) type 

 of inflorescence in which the flower 

 buds are axillary or lateral rather 

 than terminal (determinate) so that 

 the main stem may continue its 

 growth. (Fig. 22.) 



Indigenous: Native. Thus, Achillea 

 lanulosa is the common indigenous 

 yarrow of the western United 

 States, while A. millefolium is the 

 common yarrow introduced from the 

 Old World. 



Indurated: Hardened and stiffened. 



Indusium (pi. 4a) : The thin, scalelike 

 outgrowth of the leaf of a fern 

 forming a covering for the imma- 

 ture sori, or fruiting dots. 



Inferior: Being in a lower position or 

 having the base attached below some 

 other organ. Said especially of the 

 ovary when adnate to the hypan- 

 thium and having the calyx lobes 

 and other floral envelopes (if any) 

 above it. 



Inflorescence: The flowering part of a 

 plant, and especially the mode of 

 its arrangement. 



Infra-: A prefix signifying below. 



Innovation : An offshoot from the main 

 stem, which frequently becomes es- 



