Poison oak

Oak Oak ([=o]k), n. [OE. oke, ok, ak, AS. [=a]c; akin to D. eik, G. eiche, OHG. eih, Icel. eik, Sw. ek, Dan. eeg.] [1913 Webster] 1. (Bot.) Any tree or shrub of the genus {Quercus}. The oaks have alternate leaves, often variously lobed, and staminate flowers in catkins. The fruit is a smooth nut, called an {acorn}, which is more or less inclosed in a scaly involucre called the cup or cupule. There are now recognized about three hundred species, of which nearly fifty occur in the United States, the rest in Europe, Asia, and the other parts of North America, a very few barely reaching the northern parts of South America and Africa. Many of the oaks form forest trees of grand proportions and live many centuries. The wood is usually hard and tough, and provided with conspicuous medullary rays, forming the silver grain. [1913 Webster]

2. The strong wood or timber of the oak. [1913 Webster]

Note: Among the true oaks in America are:

{Barren oak}, or

{Black-jack}, {Quercus nigra}.

{Basket oak}, {Quercus Michauxii}.

{Black oak}, {Quercus tinctoria}; -- called also {yellow oak} or {quercitron oak}.

{Bur oak} (see under {Bur}.), {Quercus macrocarpa}; -- called also {over-cup} or {mossy-cup oak}.

{Chestnut oak}, {Quercus Prinus} and {Quercus densiflora}.

{Chinquapin oak} (see under {Chinquapin}), {Quercus prinoides}.

{Coast live oak}, {Quercus agrifolia}, of California; -- also called {enceno}.

{Live oak} (see under {Live}), {Quercus virens}, the best of all for shipbuilding; also, {Quercus Chrysolepis}, of California.

{Pin oak}. Same as {Swamp oak}.

{Post oak}, {Quercus obtusifolia}.

{Red oak}, {Quercus rubra}.

{Scarlet oak}, {Quercus coccinea}.

{Scrub oak}, {Quercus ilicifolia}, {Quercus undulata}, etc.

{Shingle oak}, {Quercus imbricaria}.

{Spanish oak}, {Quercus falcata}.

{Swamp Spanish oak}, or

{Pin oak}, {Quercus palustris}.

{Swamp white oak}, {Quercus bicolor}.

{Water oak}, {Quercus aquatica}.

{Water white oak}, {Quercus lyrata}.

{Willow oak}, {Quercus Phellos}. [1913 Webster] Among the true oaks in Europe are:

{Bitter oak}, or

{Turkey oak}, {Quercus Cerris} (see {Cerris}).

{Cork oak}, {Quercus Suber}.

{English white oak}, {Quercus Robur}.

{Evergreen oak},

{Holly oak}, or

{Holm oak}, {Quercus Ilex}.

{Kermes oak}, {Quercus coccifera}.

{Nutgall oak}, {Quercus infectoria}. [1913 Webster]

Note: Among plants called oak, but not of the genus {Quercus}, are:

{African oak}, a valuable timber tree ({Oldfieldia Africana}).

{Australian oak} or {She oak}, any tree of the genus {Casuarina} (see {Casuarina}).

{Indian oak}, the teak tree (see {Teak}).

{Jerusalem oak}. See under {Jerusalem}.

{New Zealand oak}, a sapindaceous tree ({Alectryon excelsum}).

{Poison oak}, a shrub once not distinguished from poison ivy, but now restricted to {Rhus toxicodendron} or {Rhus diversiloba}.

{Silky oak} or {Silk-bark oak}, an Australian tree ({Grevillea robusta}). [1913 Webster]

{Green oak}, oak wood colored green by the growth of the mycelium of certain fungi.

{Oak apple}, a large, smooth, round gall produced on the leaves of the American red oak by a gallfly ({Cynips confluens}). It is green and pulpy when young.

{Oak beauty} (Zo["o]l.), a British geometrid moth ({Biston prodromaria}) whose larva feeds on the oak.

{Oak gall}, a gall found on the oak. See 2d {Gall}.

{Oak leather} (Bot.), the mycelium of a fungus which forms leatherlike patches in the fissures of oak wood.

{Oak pruner}. (Zo["o]l.) See {Pruner}, the insect.

{Oak spangle}, a kind of gall produced on the oak by the insect {Diplolepis lenticularis}.

{Oak wart}, a wartlike gall on the twigs of an oak.

{The Oaks}, one of the three great annual English horse races (the Derby and St. Leger being the others). It was instituted in 1779 by the Earl of Derby, and so called from his estate.

{To sport one's oak}, to be ``not at home to visitors,'' signified by closing the outer (oaken) door of one's rooms. [Cant, Eng. Univ.] [1913 Webster]