oppositipetalous 
Ornithophilae 
opposite leaves; (2) opposite a 
leaf, as a tendril; oppositipet’- 
alous, -lus (re'radov, 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 (dys, dyews, sight, 
ome pua, a seed), tubercles on the 
surface of some Algals containing 
spores (Lindley). 
Opsig’ony (dyvyovos, 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’wlar, orbicula’ris (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. 
Orbil'la (orbis, an orb), the shield of 
certain Lichens, as in Usnea. 
Orchel’la, a general term for Lichens 
which yield dyes, as Lecanora, 
Roccella, ete. 
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 
Lirmus, a valuable dye from 
Lecanora tartarea, Ach., and other 
Lichens. Bs 
Or’cin, the colouring principle from 
various tinctorial Lichens. 
+ 
+ 
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orculaeform’is (orcula, » small tun, 
Jorma, 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 ~ Character, that 
which marks it off from kindred 
orders. 
Or’gan (8pyavoy, 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; organ’ic, 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 
(yévos, race, offspring), or Organo- 
gen’esis (yévecis, beginning), the 
formation and development of 
organs from their primitive condi- 
tion; adj. organogenet/ic; Orga- 
nog’raphy (ypddw, I write); Orga- 
nol’ogy (Adyos, discourse), the study 
of organs and their relations; Or’- 
ganoid (eldos, like), an organ of 
apparently unknown function 
(Swingle) ; Or’ganism, a body pos- 
sessing organic structure ; organo- 
plastic (aAaorixds, suitable for 
being wrought), with the power of 
producing organs. 
Or'gya (épyud, 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. 
Orifice, Orific’tum (Lat., an opening), 
an opening by which spores, ete., 
escape ; ostiole. 
Orig’oma = ORycomA. 
Ornithoph’ilae (dpyis, dpvidos, a bird, 
gréw, I love), plants habitually 
