oppositipetalous 



OrnithopMlafe 



opposite leaves ; (2) opposite a 

 leaf, as a tendril; oppositipet'- 

 alous, -lus (ire'raXov, a flower-leaf), 

 placed before a petal ; oppositisep'- 

 alous ( + SEPAL), situated before a 

 sepal; oppositi'vus (Lat.), when 

 one part stands before another, the 

 reverse of " alternate." 



Opseosper'mata (6^iy, tfi/'ews, sight, 

 ffirepua, a seed), tubercles on the 

 surface of some Algals containing 

 spores (Lindley). 



Opsig'ony (6\//iyovos, posthumous), the 

 production and development of 

 proventitious buds (Wittrock) ; cf. 

 PROLEPSIS. 



op'timal (optimus, best), the most 

 advantageous for an organism or 

 function; Op'timum refers to the 

 degree of temperature, light, etc., 

 which best conduces to the vital 

 activities of a given organism. 



O'rae (ora, extremity) Radi'cum = 

 SPONGIOLES. 



Or'ange, (1) the fruit of Citrus Aur- 

 antium, Linn. ; (2) a secondary 

 colour, red and yellow combined, 

 taking its name from the tint of 

 the fruit mentioned. 



orbic'ular, orbiculafris (Lat., cir- 

 cular), of a flat body with a cir- 

 cular outline ; orbic'ulate, orbicu- 

 la'tus, disk- shaped ; Orbic'ulus, (1) 

 the fleshy corona in the genus 

 Stapelia ; (2) a round flat hymen- 

 ium in Fungi. 



OrbiTla (orbix, an orb), the shield of 

 certain Lichens, as in Usnea. 



Orchel'la, a general term for Lichens 

 which yield dyes, as Lecanora, 

 Roccdla, etc. 



orchida'ceous, -eus, (1) furnished with 

 two tubers at the roots, as species 

 of the genus Orchis and its allies ; 

 (2) pertaining to the order Or- 

 chideae ; orchid'eous, relating to 

 the Orchideae. 



Or'chil, also known as CUDBEAR, and 

 LITMUS, a valuable dye from 

 Lecanora tartarea, Ach., and other 

 Lichens. 



Or'cin, the colouring principle from 

 various tinctorial Lichens. 



177 



orculaeform'is (orcula, a small tun, 

 forma, shape), used by Koerber for 

 cask-shaped Lichen-spores. 



Or'der, Or' do (Lat., methodical ar- 

 rangement), in botany, a group 

 between genus (tribe, suborder), 

 and class ; or'dinal, relating to 

 an order, as ~ Char'acter, that 

 which marks it off from kindred 

 orders. 



Or'gan (6pyavov, an instrument), any 

 definite part of a structure, as a 

 cell, a fibre, a leaf, etc. ; Or'gans of 

 Reproduc'tion, those which are con- 

 cerned in the production of seeds 

 or spores ; in Phanerogams the 

 stamens and pistils are so termed ; 

 ~ of Vegeta'tion, those connected 

 with the growth simply, as roots 

 and leaves; organic, organ' 'icus, 

 relating to living organs ; <~ Cen'tre, 

 the point or axis around which 

 growth takes place, it may not be 

 the structural centre ; Organog'eny 

 (7<^os, race,^ offspring), or Organo- 

 gen'esis (yevevis, beginning), the 

 formation and development of 

 organs from their primitive condi- 

 tion ; adj. organogenet'ic ; Orga- 

 nog'raphy (ypdtpw, I write) ; Orga- 

 nol'ogy (\67os, discourse), the study 

 of organs and their relations ; Or 7 - 

 ganoid (elSos, like), an organ of 

 apparently unknown function 

 (Swingle) ; Or'ganism, a body pos- 

 sessing organic structure ; organo- 

 plas'tic (7rAa<7Tt/cos, suitable for 

 being wrought), with the power of 

 producing organs. 



Or'gya (opyvta, a fathom), six feet in 

 height; orgy'alis, a fathom long, 

 the height of a man. 



Orienta'tion (oriens, the east), (1) the 

 correct placing with regard to the 

 quarters of the compass ; (2) gene- 

 rally means relative position, as 

 applied to organs, etc. 



Or'ifice, Orific'ium (Lat., an opening), 

 an opening by which spores, etc., 

 escape ; ostiole. 



Orig'oma = ORYGOMA. 



Ornithoph'ilae (6pvis, dpvldos, a bird, 

 ^w, I love), plants habitually 



