EXPLANATION OF TERMS. 



481 



Qynostemium. Compound structure form- 

 ed by the adhesion of androecium to 

 gynaeceum. 



Handle. In Characeae : same as manu- 

 brium. 



Haustorium. Special organ of attachment 

 and suction. 



Head. In Phanerogams : same as capi- 

 tulum. 



Head-cell. In Characeae. Same as capi- 

 tulum. 



Helicoid cyme. Same as bostryx. 



Hemicyclic. A spiral flower in which 

 the passage from one series of members 

 to the succeeding series, as from calyx to 

 corolla, coincides with a cycle of the 

 phyllotaxis, is termed by Braun hemi- 

 cyclic. Coinp. acyclic. Sachs applies 

 the term also to flowers which are in 

 part spiral and in part cyclic. 



Hermaphrodite. Of the flower : same as 

 bisexual. 



Hesperidium. Superior polycarpellary 

 syncarpous plurilocular berry with spongy 

 rind and pulp formed in numerous hairs 

 on inner surface of back and sides of 

 the carpels. 



Heterocyst. In Nostocaceae : cell inter- 

 posed at intervals on the filaments, 

 differently coloured, larger and with more 

 watery contents than the other cells and 

 with no capacity for further development. 



Heterodromy of spirals. Difference in 

 direction of the genetic spiral in branch 

 and parent axis. Comp. homodromy. 



Heteroecious. In Fungi : forms which pass 

 through different stages of development 

 on different hosts are termed heteroecious. 

 Same as metoecious. Comp.autoecious. 



Heterogony. Different relationships of a 

 definite character in respect of height of 

 anthers and stigma in hermaphodite 

 flowers in individuals of same species. 

 Same as heterostyly. Comp. homogony. 



Heteromerous. In Lichens : a thallus 

 with stratified tissue owing to algal cells 

 forming a gonidial layer and dividing the 

 hyphal tissue into an outer and an inner 

 stratum is termed heteromerous. Comp. 

 homoiomer ous . 



Heterosporous. Having more than one 

 kind of asexually produced spore. In 

 Vascular Cryptogams : having macro- 

 spores (female spores) and microspores 

 (male spores). Comp. homosporous. 



Heterostyly. Same as heterogony. 



Hilum. Scar on seed-coat left by separa- 

 tion of seed from its attachment either to 

 funiculus or placenta ; it marks the base 

 of the seed. The term is extended to 

 the ovule and denotes the point in it 

 which will become the hilum in the seed. 



Homodromy of spirals. Uniformity in 

 direction of the genetic spiral in branch 

 and parent axis. Comp. heterodromy. 



Homogamy. Synchronous maturity of 

 the two kinds of sporophyll in a herma- 

 phrodite flower. Comp. dichogamy. 



Homogony. Uniform relationship in respect 

 of height of anthers and stigma in herma- 

 phrodite flowers in individuals of same 

 species. Same as homostyly. Comp. 

 heterogony. 



Homoiomerous. In Lichens : a thallus 

 with algal cells and hyphae distributed 

 uniformly and in about equal propor- 

 tion is termed homoiomerous. Comp. 

 heteromerous. 



Homologous. Having the same position 

 and development. 



Homosporous. Having asexually pro- 

 duced spores of only one kind. Comp. 

 heterosporous. 



Homostyly. Same as homogony. 



Hormogonium. In Nostocaceae : row of 

 roundish cells from which new coenobia 

 are formed. 



Hydrophilous. Pollinated by agency of 

 water. Comp. anemophilous, zoidio- 

 philous. 



Hymenial gonidia. In Lichens : algal 

 cells in the sporocarp. 



Hymenium. In Fungi : stratum or aggre- 

 gation of spore-mother-cells on a sporo- 

 carp or other sporiferous body. 



Hymenophore. In Fungi : part bearing 

 hymenium. 



Hypha. The element of a thallus in 

 Fungi ; a cylindric thread-like branched 

 body consisting of a membrane enclosing 

 protoplasm, developing by apical growth, 

 and usually becoming transversely septate 

 as it developes. 



Hypobasal. Behind the basal wall ; said 

 of the posterior half of a proembryo. 

 Comp. epibasal. 



Hypocotyl. Stem of an embryo below 

 the cotyledons, 



Hypocotyledonary. Below the cotyledons. 

 Comp. epicotyledonary. 



Hypodermal. Beneath the epidermis. 



Hypogynous. On the torus below the 

 ovary. Comp. epigynous, perigynous. 



Hypophloeodic. Living in the periderm ; 

 said of some Lichens. 



Hypophysis. In Angiosperms : cell from 

 which the primary root and root-cap of 

 the embryo are derived. 



Hypothallus. In crustaceous Lichens : 

 marginal out-growth of hyphae, often 

 strand-like, from the thallus. 



Hypothecium. Layer of hyphal tissue 

 immediately beneath an hymenium. 

 Same as subhymenial layer. 



Hypsophyll. Bract. 



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