plaoentiform 



Plant 



placen'tiform, placentiform'is {for- 

 ma, shape), quoit-shaped or like a 

 flat cake; Placen'toid {eWos, resem- 

 blance), organs described by Chatin 

 as occurring in the anthers of certain 

 Dicotyledons to assist in the dis- 

 persion of pollen. 



placochromat'ic (irAdl, irxdicos, a flat 

 body ; XP<*'A"*'''"'^^> relating to 



- colour), used of Diatoms with endo- 

 chrome in plates or discs ; cf. 



COCCOCHROMATIC. 



plaeo'des {T\aKii>STjs, flat), used by 

 Koerber for Lichens resembling a 

 rounded plate in figure. 



plaeo'dioid {elSos, resemblance), like 

 the genus Flacoduim, with orlDicular 

 thallus, adpressed and lobed. 



Placo'phytes {irAo|, a flat body ; (pxrrov, 

 a plant), a tei-ra applied by Schuett 

 to the Peridineae, Diatomaceae and 

 Desmideae ; cf. Saccophytes ; Pla- 

 o'oplast {irKaarrhs, moulded), elaio- 

 plasts attached to the inner surface 

 of the margin of the chromophores 

 in certain Diatoms (Mereschkowsky). 



Plad'oboles |trisyll.]> Pladob'olae 

 {vXdSosy moisture ; $o\ls, thrown), 

 plants distributed by the action of 

 damp (Clements). 



plagiod'romons {TrXdyios, oblique ; 

 Sp6/j.os, a course), applied to tertiary 

 leaf-veins when at right-angles to 

 the secondary veins ; Plagio-heliot'- 

 Topism (+ Heliotropium) = Pla- 

 GioPHOTOTROPisM ; Plagiophoto- 

 tax'y {<pa>s, <puTi)s, light ; rd^is, 

 order), the oblique arrangement of 

 chlorophyll granules with regard 

 to incident light (Oltmanns) ; plagio- 

 phototrop'ic {rpov^, a turning), 

 assuming an oblique position to 

 the rays of light, as the leaflets 

 of Robvnia, Trcvaeolum, etc. 

 (Oltmanns) ; Plagiophotot'ropism, 

 the condition itself; plagiotrop'ic, 

 having the direction of growth 

 oblique or horizontal ; Plagfiot'ropism, 

 the condition described. 



plain, applied to a margin which is 

 not undulate, though it may be 

 sinuate (Crozier). 



plait'ed, plicate. 



plane, pla'nus (Lat.), level, even, flat ; 

 Plane of Inser'tion, a plane Avhich 

 passes through the point of inser- 

 tion of a lateral organ and coincides 

 with the main axis and that of the 

 organ ; -^ of Sym'metry, that which 

 divides an object into symmetrical 

 halves ; — prm'cipal - , in a flattened 

 seed, the plane of the longer axis in 

 transverse section ; sec'ondary '~, 

 at right angles to the last, the 

 shorter axis ; planius'culus (Lat.), 

 nearly flat. 



Planktorog^ [irXayKr'bs, wandering ; 

 x6yos, a discourse), the department 

 of pelagic botany, that is, of the 

 floating organisms in the ocea,n ; 

 Plank'ton, free-swimming or floating 

 oceanic life ; fresh'water '-' , that of 

 lakes or rivers ; nerit'ic '^ , found 

 near the coast ; ocean'ic --' , pelagic, 

 far from land ; tycholimnet'ic '^ , 

 false plankton, Algae at first fixed, 

 but afterwards buoyed up by gas, 

 and floating ; '- Form'ation, a 

 community of free, floating plants ; 

 Planktond'ogy = PLANKTOLOfiY ; 

 Plank'tophyte {<Pvt6i^, a plant), a 

 plant forming an integial part of 

 the plankton (Forel). 



Plan'ogamete {-TrXdvos, wandering ; 

 yafxeTTjs, a spouse), a mobile ciliated 

 gamete or zoogamete, as in Chloro- 

 phyceae ; Plan'ospore {a-irop^, a 

 seed), Sauvageau's term for a motile 

 zoospore. 



Plant, Playi'ta, a vegetable production 

 nourished by gases or liquids and 

 not ingesting solid particles of food 

 (except in the plasmodial stage of 

 Myxogastres) ; '~ Buirions = Coal- 

 BALLs ; ~ Cane, the first year's 

 growth of the sugar-cane from seed ; 

 /- Cas'ein, a substance akin to 

 animal casein ; ^ Com'mune, plants 

 which are usually found in the same 

 formation (Schimper) ; ~ Forma'- 

 tion, an assemblage of plants living 

 together in a community under 

 the same environment, as a moor 

 or wood ; -^ Pathorogy, the study 

 of . plant-diseases ; •^ -plankton 

 (-f Plankton), the same as Phyto- 



288 



