_Nucleus_, the reproductive germ in the spore.

_Obconic_, inversely conical.

_Obcordate_, like an inverted heart.

_Oblique_, slanting.

_Oblong_, longer than broad.

_Obovate_, inversely egg-shaped, broadest at the apex.

_Obtuse_, blunt or rounded.

_Ochrospore_, ochre-colored spore.

_Orbicular_, having the form of an orb.

_Order_, group of a cla.s.sification intermediate between tribe and family.

_Ostiole_, _ostiolum_, mouth of the perithecium; orifice through which the spores are discharged.

_Ovate_, egg-shaped.

_Pallid_, pale, undecided color.

_Papillate_, _papillose_, covered with soft tubercles.

_Paraphyses_, sterile cells found with the reproductive cells of some plants.

_Parasitic_, growing on and deriving support from another plant.

_Partial_, of a veil clothing the stem and reaching to the edge of the cap but not extending beyond it.

_Patent_, spreading.

_Pectinate_, toothed like a comb.

_Pedicel_, foot-stock.

_Pedicillate_, having a pedicel.

_Pelliculose_, furnished with a pellicle or distinct skin.

_Penciled_, with pencil-like hairs either on the tip or border.

_Peridium_, general covering of a puff-ball, simple or double, dehiscent or indehiscent at maturity.

_Perithecia_, bottle-like receptacles containing asci.

_Peronate_, used when the stem has a distinct stocking-like coat.

_Persistent_, inclined to hold firm, tenacious.

_Pervious_, forming an open tube-like pa.s.sage.

_Pileate_, having a cap.

_Pileoli_, secondary pilei; arising from a division of the primary pileus.

_Pileus_, the cap, receptacle, or one part of a mushroom; other parts are the stem and gills.

_Pilose_, covered with hairs.

_Pits_, depressions in cells or tubes resembling pores, applied also to hollow depressions in the surface of the cap of the morel.

_Plumose_, feathery.

_Pore_, orifice of the tubes of polypores.

_Poriform_, in the form of pores.

_Porous_, having pores.

_Powdery_, covered with bloom or powder.

_Projecting_, the anterior end jutting out beyond the margin.

_Proliferous_, applied to an organ which gives rise to secondary ones of the same kind.

_Pruinose_, covered with frost-like bloom.

_Pruniform_, plum-shaped.

_p.u.b.escent_, downy.

_Pulverulent_, covered with dust.

_Pulvinate_, cushion-shaped.

_Punctate_, dotted with points.

_Pyriform_, pear-shaped.

_Quaternate_, arranged in groups of four.