hederaceous 



Heliotropiem 



hedera'ceous, Jiedcra'ceus {Hedcra, ivy ; 

 + ACEOUS, (1) pertaining to \\j \ 

 {%) resembling ivy in habit ; hed'- 

 eral, composed of ivy ; hederif er- 

 ous [fcro, I bear), ja-odncing ivy; 

 Hed'erose, a sugar contained in ivy, 

 Bedera Hch'x. 



Hedi'um, or Hedi'on {fSos, a base), a 

 succession of plants on residuary 

 soils (Clements). 



He'gemon I {riyeiJLUjv, a leader), fibro- 

 vascular tissue. 



Hekis'totherm (t^/cjo-tos, the smallest; 

 Oep/Jir}, heat), a plant which needs 

 Viut little lieat, and can withstand 

 long periods of darkness (Warming) ; 

 adj. hekistotherm'ic. 



Hel'ad (eAoj, a marsh ; + ad), a marsh - 

 plant ; Heleoplank'ton, or Helei' 

 oplankton (+ Plankton), the float- 

 ing vegeti<tiou of marshes, which 

 overpowers the animal plankton ; it 

 diflers from Fotamoplankton by 

 less motion of the water (Zimmer). 



Helcot'ropism (fAKco, I drag ; tpotttj, a 

 turning), compulsory attraction of 

 plants ; a correction of Elco- 



'J HO PI KM. 



heliaca'lis (tiXixkos, belonging to the 

 sun), heliacal ; spiral. 



He'liad {r)\ios, the sun), a heliophyte 

 or sun-loving plant, adajtted to full 

 ex I osure (Clements' ; He'lias, a " sun 

 funn " or heliophyte. 



helianth'ine, relating to Hclianilms; 

 Helian'thon, Clements's term for a 

 family of Hclinnthns. 



Helichry'sin, the yellow colouring 

 matter of several s[)ei-ies of Ilcli- 

 chrj/sirm. 



helic'iform ihrlix, a snail ; forma, 

 shai>c), coiled like a snail shell. 



H^ricism (e\i|, fhiKos, twisted), a 

 torsion which shows itself usually 

 at an advanr-t-d ]>eriod of ]»lant-life, 

 as the tendrils and fruit of Sircpto- 

 carpug ; Hel'lcocarp {nap-nos, fruit), 

 Nicotra's term for a fruit wliose 

 constituent carpels are arranged in a 

 spiral : helicogy'rate, hclicuyn'raius 

 (gi/rafvs. turned iu a circle), having 

 a riilg cariied oblicpiely round as the 

 annulus in some Ferns ; hel'icoid. 



helicoid' cii.'^ {fldos^ like), coiled into 

 a helix, or like a snail-shell ; '- Cells, 

 terminal cells, which are usually 

 branched, of Pithophora (Wittrock) ; 

 ~ Cyme, a sjanpodial inflorescence 

 Avhose lateral branches are all de- 

 veloped on one side, a bostryx, or 

 drepanium ; in some text-books this 

 is erroneously called "scorpioid"; 

 ~ Cyst'oliths, twisted cystoliths ; 

 ~ Dichot'omy, when in two unequal 

 branches, the more vigorous one is 

 uniformly on the same side ; ~ 

 Inflores'cence, when the flowers are 

 in a single row ; ~ unip'arous Cyme, 

 a bostiyx ; helicoi'dal, spirally 

 twisted, in the manner of a snail- 

 shell ; Helicomor'phy {uopcpr}, shape), 

 term covering the young and adult 

 forms of leaf in heteroplastic plants 

 (Diels). 

 he'lio- {TfjKios, the sun), Drude's pre- 

 flx to his groups de})ending upon 

 the sun in summer for the vege- 

 tation period; helioph'ilous, -?(5 

 {(piKecti, I love), adapted to full 

 exposure to the sun ; helioph'obic 

 {(po^^u, I dread), shunning the 

 light), negatively heliotropic ; helio- 

 ph'obous {(po^eu), I fear), ada})ted to 

 a very small amount of light ; He'lio- 

 phyll {(pvWov, a leaf), a leaf of a 

 Hei.ioi'HYTE ; He'Uophytes, -phy'ta 

 {(pvTov, a plant), ))lants adapted t^ 

 full sunlight ; Heliophyti'a, forma- 

 tions of such plants (Clements) ; 

 Helio'sis, injury done by sun -burn ; 

 Helioetroph'ism (4- Stuoi'III.sm), a 

 tendency to twist, in response to 

 light (Ffeller) ; HeHotax'is {rd^a, 

 arrangement), the turning of an 

 organism such as a sjiore, in relation 

 to light; Heliotor'tism {torhui, 

 twisted), torsion caused by incidence 

 of light (Schwendener and Krabbe) ; 

 heliotrop'ic (rpSiros, direction), turn- 

 ing towards the light ; ~ An'gle, 

 the angle of incidence at which light 

 lias the most stinmlating elfect ; 

 Hsliot'ropism, the act of turnihg 

 towards the sun or source of light ; 

 neg'ative ~, shunning light ; pos'i- 

 tive ~, growing in the direction of 



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