Duct 



dysantMc 



Diict, Duct' us (Lat., led, conducted), 

 an elongated cell or tubular vessel, 

 espenially occurring in the fibro- 

 vascular portions of plants ; an'nular 

 '~, the secondary thickenings occur- 

 ring more or less in the form of rings ; 

 closed '^ , long cells, not continuous, 

 but with the intervening septa re- 

 maining ; dott'ted '-', = BoTii- 

 RENCHYMA ; intercell'ular '^, pas- 

 sages between the cells ; retic'ulated 

 '^ , where the markings seem to form 

 a network ; scalar'iform -^ with 

 ladder-like markings as in Ferns. 



durcis (Lat.), sweet, extended to any 

 kind of taste which is not acrid ; 

 Dul'cite, a crystalline substance 

 from Melavipyrum, also found in 

 Madagascar Manna. 



du'metose, dumeto'sus [dumetum, a 

 thicket), bushy, relating to bushes ; 

 Dume'tum, a thicket. 



dumose' {dumo'sus, bushy), full of 

 buslies, of shrubby aspect ; Du'mus 

 (Lat.), a bush. 



Dune, undulating banks of blown sand, 

 with characteristic vegetation ; cf. 

 Thintum. 



duods'ni (Lat.), by twelves, growing 

 by twelves. 



du'plex (Lat.), double; du'plicate, 

 duplica'tns, double or folded, twin ; 

 -^ Par'asitism, self-parasitism, as in 

 the case of mistletoe upon mistletoe ; 

 Duplica'tion, doubling, Chorisis ; 

 duplica'to-crena'tus. doubly-crenate ; 

 ~ denta'tus. doubly-toothed ; '-- 

 pinna'tus, bipinnate ; ~ serra'tus, 

 doubly -serrate ; -^ terna'tus, biter- 

 nate ; duplo = twice as many ; in 

 Greek compounds it is diplo. 



Dura'men (Lat., a hardened vine 

 branch), the heartwood of an exo- 

 genous stem, wlii h has become 

 hardened by deposits. 



Durifrutice'ta (du7-us, hard ; frutice- 

 tunt. a thicket), sclerojihyllous scrub 

 formations ; Durilig^o'sa [lignosus, 

 woody), trees and shrubs which have 

 sc'erophyl ous leaves or green axes 

 which serve as le ives ; Duripra'ta 

 {pratum, a meadow), where the 

 dominant species are strengthened 



by mechanical tissue, largely consist- 

 ing of grasses and sedges ; Durisil'vae 

 {silva, a wood), sclerophyllous forest 

 formations, as of Quercus Ilex in the 

 Mediterranean region and Eucalyp- 

 tus in Australia. 



Dust, Blair's word for Pollen ; dust'y, 

 covered Avith granulations lesem- 

 bling dust ; or powdered, farinose. 



dwarf, of small size or height com- 

 pared with its allies ; ~ Male, a 

 short-lived filament of a few cells 

 in Oedogoniaceae, the upper cells 

 being antheridia. 



Dy'ad (5uos, hvaZos, two), (1) a sub- 

 division of a Tetrad by mitosis, 

 again dividing into single elements 

 (Calkins) ; (2) a bivalent chromo- 

 some. 



Dyas'ter (8«5o, double ; a<Tr))p, a star), 

 the stage of nuc ear division when 

 the rays of linin split longitudinally 

 and two stars are formed which move 

 apart, ending with the formation of 

 daughter-skeins ; dyblas'tus {^\a<r- 

 rhs, a bud), two-celled, applied to 

 Lichen spores ; Dycle'sium, or 

 Dyclo'sium, see Diclesium. 



dynamic {5uva/xLs, power), applied to 

 tissue which is capable of strongly 

 swelling on one side ; ~ Cell, any 

 thick-walled prosenchymatous ele- 

 ment, having its molecules or micellae 

 in transverse rings, which undergoes 

 marked longitudinal contraction in 

 water (Eichholz) ; Dynam'ia, used 

 by Linnaeus to express the degree 

 of development of stamens, as Didy- 

 namia and Tetradynamia, applied 

 to flowers where resfiectively two 

 and four stamens have longer fila- 

 ments than the remaining two ; 

 dy'namo-staL'ic {(rrdais, a standing) 

 El'ements, hygroscopic motor-cells 

 (Eichholz) ; Dyne, the unit of force 

 expressed by the weight of one 

 gramme moving one centimetre in 

 one second of time (Errera) [= CGS]. 



dyploste'monous = diplostemonous. 



Dyploteg'ia = Ditlotegia. 



dysanth'ic {avdos, a flower), fertiliza- 

 tion by the pol'en from a difl'erent 

 plant (K. Pearson). 



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