Exochite 



Expansion 



ing of MESISTEM "thickening ring" 

 and PEKISTEM, young cortex ; it is 

 the tissue of protomeristem which 

 is not young pith. 



Ex'ochite (e'w, outside, X' 1 """? a tunic), 

 the outermost membrane of the egg 

 in Fucaceae (Farmer) ; Exocor'tex, 

 (cortex, bark), a special triple layer 

 in the roots of saprophytic Orchids ; 

 Exoderm'is (dep^a, skin), the outer- 

 most cortical layer of the adult 

 root, answering to the hypoderma 

 of the stem. 



Excoe'mum (e', out, oi>dw, I issue), 

 a fringe or tuft of hair at the base 

 of the glumes in some grasses 

 (Richard) ; exocatad'romous ( 4- 

 CATADROMOUS), when Ferns in their 

 nervation have their stronger 

 pinnules anadromous, and their 

 weaker catadromous ( Prantl ) ; 

 Exog'amy (yd/j.os, marriage), the 

 tendency of closely allied gametes to 

 avoid pairing ; exog'enous exog'enus 

 (yevvdu, I bring forth), (1) growing 

 as the wood of Dicotyledons ; (2) 

 arising from superficial tissue ; 

 Ex'ogens, Exog'enae, plants which 

 increase in growth by the addition of 

 wood on the outside beneath the 

 constantly widening bark ; Exog'y- 

 nOTis,exoy'ynus (yvvr], woman), where 

 the style is exserted beyond the 

 flower ; Exoisog'amy ( + ISOGAMY), 

 when a gamete will pair only 

 with a similar gamete of another 

 brood (Hartog) ; exonas'tic (vac-ros, 

 pressed close), in anatropous or 

 campylotropous ovules when the 

 curvature is horizontal towards 

 the median nerve of the side of 

 the upper face of the carpel 

 (Van Tieghem) ; cf. ENDONASTIC ; 

 Exoneuro'sis (vevpov, a nerve), the 

 separation of veins in appendicular 

 organs, and their reappearance as 

 teeth, spines, or bristles, as in the 

 Barberry (Clos) ; Exoperid'ium ( + 

 PERIDIUM), the outer layer of the 

 peridium of such Fungi as Lycoper- 

 don, which peels or flakes oft' on 

 maturity ; exophyll'ous -u* (<pv\\oi>, 

 a leaf), not having a foliaceous 



sheath, with naked cotyledons ; 

 exop'tile, exop' tills (TTTL\OV, a 

 wing) = EXOPHYLLOUS, said of 

 an embryo whose plumule is naked 

 upon, or between cotyledons and 

 not rolled up in one (Lindley) ; 

 Exorhi'zae (ptfa, a root), = EXOGENS; 

 exorhi'zal, exorhiza'lis, the radicle 

 not sheathed, so the primary root 

 in germination has no covering to 

 pierce; Exos'mose,.>.smo'si.s(ci<r / u.6s, 

 a thrusting), the passage through a 

 membrane outwards from a thin to 

 a dense fluid ; Exosclero'tes (<TK\r)p6s, 

 hard), sclerotia which are external 

 to the surface of Agarics ; Ex'- 

 ospore, Exospor'ium (a-n-opd, seed), 



(1) the outer covering of the spore ; 



(2) a thick coat developed from the 

 periplasm round the oospore in 

 Peronosporeae ; exos'porous, hav- 

 ing scattered spores, as Fungi ; Ex'- 

 ostouie, Exost'oma (arofj-a, amouth), 

 the foramen of the outer coat of the 

 ovule ; Exosto'sis (oareov, bone), 

 (1) the nodules on roots of Legumi- 

 nosae ; (2) the hard turgescence of 

 sound wood, showing as prominent 

 knots ; Exosty'lus ( + STYLUS), 

 Mirbel's word for fruit as in 

 Labiatae, four seemingly naked nut- 

 lets ; Exothe'cium (dr]Kr), acase), (1) 

 the outer case of the anther 

 (Henslow, Lindley) ; (2) Purkinje's 

 term for the extine or outer 

 layer of pollen-grains. 



exoteric (e^urepiKos, external), aris- 

 ing from outside the organism, the 

 opposite of ESOTERIC. 



exot'ic (ec<m/cos, foreign), not native, 

 introduced from abroad ; Exot'ics 

 are those plants which are not in- 

 digenous. 



exotroph'ic (ew, out of, rpo^rj, nourish- 

 ment), employed by Wiesner where 

 an organ or lateral shoot, as op- 

 posed to the mother-shoot, is most 

 strongly developed ; Exot'rophy, 

 development of lateral shoots 

 instead of the main axis. 



expand'ed, expan'sus (Lafc. spread 

 out), diffuse ; Expan'sion, the con- 

 dition of a flower in full perfection ; 



