paill·asse (pal´yas´) n. a sleeping mattress which is filled with straw; pallet; palliasse. [< F paillasse < Ital. pagliaccio < L palea pallet]

pa·le·o·ec·ol·o·gy (pā´lē ō ek ol´ə jē or pā´lē ō ē kol´ə jē) n. the branch of paleontology which deals with the relations of organisms to their environment and to each other, in past times. [< Gk. palaios παλαιός ancient, old in years + oîkos οἰκός house + logos λόγος word or discourse] —pa´le·o·ec·o·log´ic, adj. —pa´le·o·ec·o·log´i·cal, adj. —pa´le·o·ec·o·log´i·cal·ly, adv. —pa´le·o·ec·ol´o·gist, n.

pal·let1 (pal´it) n. 1 a bed or mattress stuffed with straw; paillasse; palliasse. 2 a small or makeshift bed, not necessarily stuffed with straw. [< ME pailet < AF paillete (< OF paille straw (< L palea chaff, straw) + -ete diminutive)]

pal·let2 (pal´it) n. 1 a flat, low platform, often made of wood, on which objects may be placed for storage or to more easily move them about. 2 a flattish instrument employed by potters in shaping vessels. 3 in music, a wooden flap faced with leather, which opens to allow air to pass to a pipe in an organ. [< MF palette small shovel]

pal·li·asse (pal´ē as´) n. a sleeping mattress which is filled with straw; paillasse; pallet. [< F paillasse < Ital. pagliaccio < L palea pallet]

palmate-pinnate adj. of a compound leaf, bearing first-order leaflets palmately, but second-order leaflets presenting pinnately.

pal·my (pä´mē or päl´mē) adj. n. —adj. -mi·er, -mi·est. 1 shaded by or abounding in palm plants. 2 resembling a palm; palmlike. 3 glorious or flourishing, or luxurious (of generalised use unrestricted to botany). —n. 1 Palmy stage name of a singer of popular music, Eve Pancharoen, born in Bangkok in 1981. 2 Palmy colloquial name for the modest city of Palmerston North, New Zealand.

pal·my·ra (päl mī´rə) n. a tall palm native to tropical Asia (Borassus flabellifer L., of the Arecaceae), bearing palmate rather than pinnate leaves, and able to be harvested in many ways for food: the sugary sapling juice can be harvested before morning, as well as inner sapling stems, the terminal bud, the sap of inflorescences, and edible jelly-like seeds. It also provides leaves used in thatching and in weaving, also previously as a natural paper, and stem fibres for rope and brushes, and also wood for construction. The sap may also be taken medicinally as a laxative. Palmyra is symbolic of Cambodia as well as of other geographic regions, and prominent in Tamil culture. [< Pg. palmeira palm tree; spelling ? influenced by city Palmyra in Syria]

pal·my·rie (päl mī´rē) n. a planting or orchard of palms. [? < E palm palm tree + OF -erie collection of; spelling ? influenced by city Palmyra in Syria]

pal·u·dose (pal´ū dōs´) adj. growing in a marsh. [< L palus marsh + -ōsus pertaining to, prone to]

pal·y·nol·o·gy (pal´ə näl´ə jē) n. the scientific study of pollen grains, as well as of spores, especially in relation to archæology and interpretation of local significance. [< Gk. palynō παλύνω scatter, strew + logos λόγος word or discourse] —pal´y·no·log´i·cal, adj. —pal´y·no·log´i·cal·ly, adv. —pal´y·nol´o·gist, n.

pal·y·no·morph (pa lin´ō môrf´) n. any of the various acid-insoluble residues of erstwhile living creatures which can be encountered in macerated sedimentary rock, under investigation for fossil remains. They comprise fossil pollen and spores, as well as various other acritarchs. [< Gk. palynō παλύνω scatter, strew + morphē μορφή form, shape]

par·a·dise (pär´ə dīs´) n. 1 a select portion of a large garden, useful for spiritual reverie. 2 a place endowing a state of pure happiness. 3 Eden, prior to the sinful choice. 4 Islam. a garden of delights which Quran promises to the faithful, upon their death. [ME < OF paradis < L paradīsus < Gk. paradeisos παράδεισος < Avestan pairidaēza παιριδαηζα enclosed area, park] —par´a·dis´i·a´cal, adj.

par·al·le·lo·dro·mous (pär´ə le lə drō´məs or pãr´-) adj. of pinnate leaf venation, having all secondary leaf veins diverge at regular intervals from the primary vein and run in parallel towards the leaf margin; penni-parallel. [NL < Gk. parállēlos παράλληλος parallel + dromos δρομος a running, or course]

pa·ra·phy·let·ic (pär´ə fī let´ ik) adj. of any grouping of organisms, together derived from a single evolutionary ancestor or ancestral group, but existing among other descendants from the same ancestor which are not considered. [< NL < Gk. para- παρά- alongside of + phyletikos φυλετικός (< phyletēs φυλέτης tribesman < phylēs φυλῆς tribe)] —pa´ra·phy´ly, n.

pa·ras·ti·chy (pə´ras´ti kē) n. -chies (-kēz). 1 in phyllotaxis, an arrangement of leaves (or branches) in an ascending spiral, usually with very short internodes. 2 a single set of leaves so aligned. [< NL < Gk. para- παρά- alongside of + stichia στίχα alignment] —pa´ras´ti·chous, adj.

par·a·wood (pär´ə wu̇d´) n. the wood of the Pará rubber tree (Hevea brasiliensis (Willd. ex A.Juss.) Müll.Arg., of the Euphorbiaceae), suitable for various types of woodwork if treated for protection from fungi and insect-borers; plantation hardwood; Malaysian oak; rubberwood.

pa·ri·e·tal (pä rī´ə təl) adj. of or pertaining to the inner wall of an enclosing structure, especially an ovary. With respect to placentation, fixed to the ovary wall, and deriving nutrition from this surface rather than the axis or base. [ME < LL parietalis pertaining to walls]

park (pärk) n. an enclosed area of land, set aside as a special reserve for: a protection of natural habitat; b provision of a vegetated area for recreation; c provision of a space for some other purpose, often at the cost of native vegetation. [ME < OF parc < Med.L parricus land held for keeping game animals < Gmc.]

parsley-piert n. any of a genus of diminutive branching annual herbs (Aphanes L., of the Rosaceae), bearing fan-shaped leaves with clasping stipules, and tiny 4-merous flowers lacking petals, native through Eurasia and Australia. It has previously been considered a sub-genus of Alchemilla L..

patch (pach) n. 1 a small plot of land largely covered by a single species. 2 an area of tissue somewhat discoloured, often due to an infection or herbivory. [ME < ONF pieche piece]

patch·ou·li (pə chü´lē) n. adj. —n. 1 a subshrub native to humid temperate forest understorey of eastern Asia (Pogostemon cablin (Blanco) Benth., of the Lamiaceae), releasing a strong, pleasant odour. 2 the aromatic oil derived from leaves harvested from this plant. —adj. of or pertaining to this plant: patchouli oil. [< Tamil paccuḷi < பச்சை (patchai) green + இலை (ellai) leaf]

patch·y (pach´ē) adj. -i·er, -i·est. occurring in, or displaying, patches.

pat·er·i·form (pat´ėr i fôrm) adj. usually of a floral structure, having the form of a shallow bowl. [< L patera dish, saucer + fōrma shape, figure, appearance]

path·o·var (path´ə vär´) n. a pathological variety of a bacterial species normally considered nonpathological. Those pathological to plants normally are named for the genus of plants sustaining infection. [< Gk. pathos πάθος suffering + E variety, on the pattern of cultivar]

pat·ty·pan (pat´ē pan´) n. adj. —n. a comparatively recent cultivar of squash (Cucurbita pepo L. var. clypeata Alefield, of the Cucurbitaceae), growing as a subshrub and bearing oblate discoid fruits (pepos), which are best eaten when immature; cymling; scallop squash. These can be greenish-white or yellow as they approach maturity. —adj. of or pertaining to this plant or its fruit. [E descriptive – a small pan for baking patties < F pâtisson scallop squash]

paw·ber·ry (pä´bãr´ē) n. in the tales of Pern, a plant native to the area of Bitra hold, and whose leaves when boiled provide a pure red pigment.

paw·paw (pä´pä´ or po´po or pô´pô´) n. the papaya tree, and/or its fruit. [< E papaya, papay < Sp. < Carib]

pea·ber·ry (pē´bãr´ē) n. -ries. a coffee seed which grows to maturity alone, rather than in the more usual facing pair, and thus matures rounded rather than flat upon one side. Seeds of this type are believed to roast more evenly and provide better coffee.

pear·main (pãr´mān´) n. any of a number of cultivars of apples, often bearing fruit with a distinctively red epidermis. Nevertheless, despite the similarity of name, these cultivars are neither more nor less similar to pears than other cultivars, nor are they always red. [< OF permain; ? < L Parmēnsis of Parma]

ped·og·ra·phy (ped äg´rə fē) n. the geography, and mapping, of terrestrial locations only, to locate soil strata and rock outcrops. [< NL pedo- a combining form meaning soil + Gk. graphē γραφή drawing, description] —ped·og´ra·pher, n.

pe·dun·cu·late (pe dung´kū lāt) adj. 1 of growth form, arising from the substrate upon a stem or peduncle, rather than lying adpressed to the substrate. 2 bearing a peduncle or peduncles, or similar stalks. 3 Informal. being borne upon a peduncle; peduncular. [< NL pedunculus (dim. of L pes foot) + -ātus provided with]

peel·er1 (pēl´ėr) n. 1 one who peels the bark off of tree trunks, or the rind off of fruits. 2 a mechanical implement designed to assist in this. [< OF pel skin/rind (< L pellem skin) + E -er one who – or that which – performs a specific action]

peel·er2 (pēl´ėr) n. Kent dial. an iron bar which is used to drill holes into the ground for planting hop poles or wattles.

peeler log n. a trunk of a cut tree (especially softwood) which is suitable for use as a source of veneer through use of a rotary lathe.

pelf (pelf) n. dial. 1 vegetable refuse consisting of weeds and shed leaves. 2 light grass and roots, raked together to be burnt. [ME < ONF pelfe < OF pelfre spoil]

pel·li·to·ry1 (pel´i tô´rē) n. -to·ries. an herb of the Mediterranean coast (Anacyclus pyrethrum DC., of the Asteraceae) bearing finely-divided compound leaves and having a hot, pungent flavour in its roots which is used medicinally as a counter-irritant. [< ME < OF peletre, peretre < L pyrethrum < Gk. pyrethron πύρεθρον pellitory, feverfew < pyros πυρός fire]

pel·li·to·ry2 (pel´i tô´rē) n. -to·ries. any of various European species of the cosmopolitan herb genus Parietaria L. (of the Urticaceae), which bear whorls of small flowers at their stem nodes, and often grow against a wall. [< OF paritaire < LL parietaria of a wall]

penetration peg n. in mycology, the special-purpose hypha which penetrates a host plant cell, generated from the appressorium. It generally possesses an abnormally high turgor pressure.

penni-parallel adj. of pinnate leaf venation, having all secondary leaf veins diverge at regular intervals from the primary vein and run in parallel towards the leaf margin; parallelodromous. [NL < L penna feather + Gk. parallēlos παράλληλος parallel]

pen·ta·car·pel·lar·y (pen´tə kär´pə lãr ē) adj. of a compound fruit, consisting of five carpels, as an apple. [< Gk. pente πέντε five + NL carpellum small fruit + E -ary connected with, pertaining to (< L -arius adjectival suffix)]

pen·ta·coc·cous (pen´tə kok´əs) adj. of a flower, possessing five carpels. [< Gk. pente πέντε five + NL coccum carpel + L -osus prone to]

pen·ta·fid (pen´tə fid´) adj. 1 split into 5. 2 split about midway into five lobes; quinquifid. [< Gk. pente πέντε five + L fid-, base of findere cleave]

pe·pine (pe pēn´) n. kernel.

pe·pin·ne·ry (pe´pin´ə rē) n. a portion of an orchard in which fruit stones are set to encourage them to grow. [< OF pepin grown from seed + ME -ery (< OF -erie noun suffix)]

pe·pi·no (pe pē´nō) n. 1 an evergreen shrub believed to be native to the northwestern Andes, although now unknown except in cultivation (Solanum muricatum Ait., of the Solanaceae); pepino dulce; melon pear. It tends to be a low-growing perennial bearing sweet berries in the form of a prolate sphere up to 8cm in length, beige in colour with purple stripes. 2 a rounded conical hill in karst terrain. [< Sp. pepino cucumber < L pepo pumpkin]

pep·per·root (pep´ə rüt´) n. the single species Dentaria incisifolia Eames, as well as many of a closely-related subset of species of genus Cardamine L. (all of the Brassicaceae), native to North America and Eurasia, and which may bear toothlike enations from their creeping rhizome; crinkleroot; toothwort. The rhizome is edible, and has also shown utility for treating certain medical complaints.

pep·ti·do·gly·can (pep´ti dō glī´kan´) n. a polymer which comprises polysaccharides and peptides, in a molecular network of essentially fixed size forming the cell wall of prokaryotes as well as of certain algæ; murein. [NL < E peptide (< peptic < Gk. peptikós conducive to digestion) + glycan monosaccharide polymers conjoined by glycosidic bonds]

per·an (pãr´an´) n. in the story The Color Least Used by Nature, by Ted Kosmatka, any of a small population of trees native to an island, and which produces a wood that is light and strong, and particularly of use for boat building. The living tree grows only on the mountain of the island, and is called the walking tree because it will attempt to leap from the mountain into the lagoon. These trees survive presently by being tethered to a rock by a rope and walking in a circle at the limit of their tether. Before people came, these trees are reputed to have walked and spoken.

per·i·chæ·ti·um (pėãr´ə kē´tē əm) or per·i·chæth (pėr´ə kēth´) n. -ti·a. the apical microphylls of moss and liverwort gametophytes, which surround the archegonium and later the sporophyte. [NL < Gk. peri πέρι all around + chaitē χαίτη flowing hair, foliage + -ion -ιον diminutive] —per´i·chæ´ti·al, adj.

per·i·cli·nal (pãr´ē klī´nəl) adj. 1 of the plane of cellular division, oriented parallel to the surface of an organ (such as the meristem), so that additional cells are produced centripetally and centrifugally, or proximally and distally. 2 of a cell wall, oriented parallel to the surface of an organ as a result of such growth. [< Gk. periklinēs περικλινής sloping upon all sides] —per´i·cli´nal·ly, adv.

pe·ri·go·ni·um (pe´ri gō´nē əm) or pe·ri·gone (pe´ri gōn´) n. -ni·a. the apical microphylls of moss and liverwort gametophytes, which surround the antheridium. [NL < Gk. peri πέρι all around + goneuō γονεύω to generate + -ion -ιον diminutive] —pe´ri·go´ni·al, adj.

per·ine (pãr´ēn´) n. in ferns of suborder Hydropteridineae Rothwell & Stockey, an outer layer to the megaspore cell wall; perispore. It is external to the exine, and may itself be composed of inner and outer layers (endoperine and exoperine), the latter of which often bears a filosum. [NL < Gk. peri- πέρι- near, around + L -inus of or pertaining to; assimilated to exine, intine]

pe·ri·plast (pe´rə plast´) n. an essentially proteinaceous intracellular structure in protists which do not form cell walls, lining the inner side of the cell membrane and contributing to the movement of these organisms (primarily confined to divisio Euglenophyta). [NL < Gk. peri- πέρι- near, around + plastos πλαστός molded, formed]

Peruvian lily n. any of the numerous herbal species of the South American genus Alstroemeria L. (of the Alstroemeriaceae), most littoral semiaquatics with brightly-coloured flowers.

pet·al·ous (pet´əl əs) adj. of a taxon or its flowers, generating and bearing petals. [ME < NL apetalus (back-formation) < Gk. a- α- absence + petalon πέταλον flower leaf + -ōsus -ωσις prone to]

pet·al·y (pet´ə lē) n. the character state of generating or possessing petals; being petalous. [< Gk. petalon πέταλον leaf + E -y abstract noun suffix]

pheasant’s-eye n. any of several erect annual herbs bearing 2-3 pinnate compound leaves and often large yellow, orange, or scarlet flowers (spp. of Adonis L., of the Ranunculaceae), native at various locations around Europe, Asia, and adjoining Africa.

phenological event n. a precisely-defined point in the life-cycle of a plant or fungus, either occurring on an annual basis or once in its life, but signifying the start or end of a phenophase. These events are often recorded as to date and time, for comparison to other years or locations.

phenological status n. a summary of the state of all registered phenophases for a particular individual, species, or community, for a particular moment in time.

phe·no·phase (fē´nō fāz´) n. a stage in the growth or annual development of a plant (or of groups of plants) which occurs for a particular period of time and can be visually discerned. Examples include such events as initial budding of leaves, or blossoming of flowers. [< Gk. phainomenon φαινόμενον that which is seen + F phase (< Gk. phasis φάσις appearance)]

phe·no·type (fē´nō tīp´) n. the set of observable characteristics of an organism, resulting both from its genotype and from interaction with its environment. —v.t. to set out clearly the observable characteristics of a particular organism – normally those expected to be shared with others of its taxon and clearly differentiating it from other taxa. [< G Phänotypus < Gk. phainomenon φαινόμενον that which is seen + typos τύπος image, type] —phe´no·typ´ic (-tip´ik), adj. —phe´no·typ´i·cal·ly, adv.

pho·to·tax·is (fō´tō tak´sis) n. -tax·es. movement of cells or organisms to or away from the stimulus of light; phototropism. [< Gk. phōtos φωτός light + taxis τάξις responsive movement (< taxō τάξω, fut. of tassō  τάσσω arrange)] —pho´to·tac´tic, adj. —pho´to·tac´ti·cal·ly, adv.

-phy·ce·æ (fī´sē ē) comb.form., suffix. ending for Latin names of classis of algæ, under the ICN. [NL] -phy´ce·an, adj.

-phy·ci·dæ (fī´sē ē) comb.form., suffix. ending for Latin names of subclassis of algæ, under the ICN. [NL]

phy·co- (fī´kō-) comb.form., prefix. referring to algæ and certain similar aquatic organisms. [< Gk. phŷkos φῦκος sea weed]

-phy·co·ta (-fī´kō´tə) comb.form., suffix. ending for Latin names of divisionis of algæ, under the ICN. [< Gk. phȳko φῦκο (comb.form for phŷkos φῦκος seaweed) + NL -ota pl. suffix (< Gk. -ōta -οτᾷ)] -phy·co´tid, adj.

-phy·co·ti·na (-fī´kō tē´nə) comb.form., suffix. ending for Latin names of subdivisionis of algæ, under the ICN. [< Gk. phȳko φῦκο (comb.form for phŷkos φῦκος seaweed) + NL -ota pl. suffix (< Gk. -ōta -οτᾷ) + -ina dim. suffix] -phy·co´ti·nid, adj.

phyl·lo·sphere (fil´ə sfēr´) n. the internal and external environment of the leaves of plants, collectively or individually. [NL < Gk. phýllon φύλλον leaf + LL sphēra (< L sphæra < Gk. sphaîra σφαῖρα ball, sphere)]

physick garden n. (obs.) a garden in which are grown various plants with known medicinal qualities. [ME < OF fisique medicine < L physica < Gk. phusikē φυσικῇ (epistēmē ἐπιστήμῃ) (knowledge) of nature]

phys·i·og·no·my (fiz´ē ä´nə mē) n. 1 the general form or appearance of an organism; morphology. 2 the study of that general form or appearance; morphology. [ME < OF phisonomie < Gk physeos φύσεος (< Ionic physios φύσιος nature, natural qualities) + gnōmōn γνώμων judge or inspector] —phys´i·og·nom´ic, adj. —phys´i·og·nom´i·cal, adj. —phys´i·og·nom´i·cal·ly, adv. —phys´i·og´no·mist, n.

-phy·ta comb.form., suffix. ending for Latin names of divisionis of plants, under the ICN. [< NL phyta plants]

-phyte (-fīt) comb.form., suffix. plant. [NL < Gk. phyton φυτόν plant]

-phy·ti·na (-fī´tē´nə) comb.form., suffix. ending for Latin names of subdivisionis of plants, under the ICN. [< Gk. phyta φυτά plants + -ina -ινα dim. suffix]

phy·to·chrome (fī´tō krōm´) n. a pigment compound, blue-green in colour, which reacts to relative proportions of red and far-red illumination, assisting plants to grow in an appropriate manner when subjected to shading. It is composed of a simple protein dimer, each monomer of which bears its own pigment chromophore. The entire compound changes form when in the presence of light to which it is sensitive. [< Gk. phyton φυτόν plant + chrōma χρῶμα colour]

phy·to·lith (fī´tə lith´) n. a rigid body composed mainly of noncrystalline silicon dioxide found either within cells or in extracellular deposits, but only produced by certain plant familia. A phytolith, because it also contains carbon, comprises a durable and useful fossil. [< Gk. phyton φυτόν plant + lithos λίθος stone]

phy·to·ness (fī´to nis) n. a diviner or pythoness, who is able – by means of a “familiar spirit” – to interpret the future and pass on spiritual advice. Sometimes used in relation to Phythia, the Delphic oracle. [< OF phitonise < Med.L phitonissa]

phy·to·phage (fī´tō fāzh´) n. 1 a virus which is capable of infecting plant cells. 2 an organism which feeds upon plants, particularly used of insects; herbivore. [NL < Gk. phyton φυτόν plant + -phagia -φαγια eating, devouring]

phy·to·pha·gy (fī´tō fā´zhē) n. the eating of plants, or plant cells. [NL < Gk. phyton φυτόν plant + -phagia -φαγια eating, devouring] —phy·toph´a·gous, adj.

phy·to·plank·ter (fī´tō plangk´ter) n. any microscopic plant which exists as a component of the plankton. [< Gk. phyton φυτόν plant + planktḗr πλανκτήρ roamer]

phy·to·plank·ton (fī´tō plangk´tən) n. that portion of the aggregate collection of planktonic organisms which comprise microscopic algae. [< G < Gk. phyton φυτόν plant + planktós πλανκτόs drifting]

phy·to·sphere (fī´tō sfēr´) n. 1 the internal and external environment of plants or with respect to plants, collectively or individually. 2 the collective habitat of plants upon the Earth (or, presumably, upon any other body in space which they may occupy). [NL < Gk. phyton φυτόν plant + LL sphēra (< L sphæra < Gk. sphaîra σφαῖρα ball, sphere)]

phy·to·tel·ma (fī´tō tel´mə) n. -ma·ta. a water body held by a terrestrial plant, either at the axil of a leaf or floral axil, or in modified leaves, or in stem recesses, or fallen leaves or fruit. [NL < Gk. phyton φυτόν plant + télma τέλμα pond]

phy·to·ther·a·pist (fī´tō thãr´ə pist) n. one who is skilled to employ phytotherapy in healing.

phy·to·ther·a·py (fī´tō thãr´ə pē) n. -pies. a medical treatment of human infirmities incorporating ingredients derived from plants (i.e. herbal remedies). [< Gk. phyton φυτόν plant + L therapia (< Gk. therapeia θεραπεία medicinal attendance and care)]

pi·co·tee (pē´kō tā´) adj. of a flower, bearing petal margins of a colour contrasting with the base colour of the petal. [< F picotée marked, pointed]

pi·lin·gi·tam (pi lin´gi tam) n. in the novel Heretics of Dune by Frank Herbert, a tree of the Old Empire valued particularly by the rich as a basis for fine woodwork. It grows as a large tree whose trunk increases greatly in diameter with age, often becoming hollow in the centre. Its wood is soft and easy to craft when freshly-cut, but once dried becomes very hard, insect-proof, anti-fungal, and fire-resistant.

Pima cotton n. 1 a particular species of cotton (Gossypium barbadense L., of the Malvaceae) whose seeds are known for their extra-long fibres (35-60mm). 2 the fibres of this species, harvested for textile use; extra-long staple cotton; sea island cotton; Egyptian cotton. [< Pima (Akimel O’otham) ethnic group, who first established cultivation of the species in Arizona]

pi·ma·li·a (pi mä´lē ä) n. in the novel Thuvia Maid of Mars by Edgar Rice Burroughs, a large shrub native to Barsoom (Mars), and which bears gorgeous flowers producing fragrant oil. [Barsoomian]

pi·men·to (pə men´tō) n. -tos. 1 allspice. 2 pimiento. [< Sp. pimiento]

pi·mi·en·to (pē´mē ān´tō) n. -tos. 1 a sweet red pepper (fruit of Capsicum annuum L., of the Solanaceae), whole, or a portion used in preparing food, such as that used to provide a pleasing colour and flavour to a pitted green olive; pimento. 2 the plant itself. [< Sp. < Med.L pigmentum spice < L pigmentum colouring]

pinch back remove extended growing tips of a plant, using finger nails, in order to augment the bushiness of the remaining plant body.

pink·root (pink´rüt´) n. 1 either of two herbs native to the Americas (Spigelia anthelmia L. and S. marilandica (L.) L., both of the Loganiaceae), and both possessing vermifuge properties; worm grass. 2 a fungal disease of onions.

pin·nat·i·lo·bate (pi nat´ē lō´bāt) adj. of a leaf blade, pinnate in form or shape and pinnately-divided, but not all the way to the central rachis, and having the pinnæ or lobes relatively large or wide. [< L pinnatus feathered + NL lobātus lobed]

pitcher plant n. 1 any of several related herbs of swampy ground in the Americas (Darlingtonia californica Torr., as well as species of Heliamphora Benth. and Sarracenia L., all of the Sarraceniaceae), which grow as rosettes of oblong insectivorous pitchers (leaves) surrounding a central leafless flowering scape. 2 an herb of swampy ground in Australia (Cephalotus follicularis Labill., of the Cephalotaceae) which exists as a basal rosette of normal foliage leaves and leaves adapted to form small lidded insectivorous pitchers surrounding a central flowering raceme of minor cymes; Australian flycatcher. 3 any of several related herbs or climbing shrubs of the genus Nepenthes L. (of the Nepenthaceae), growing in southeast Asia or Madagascar, and characterised by leaves which bear a basal foliaceous blade and produce the pitchers from an extension of the leaf midrib into an apical tendril and finally a terminal insectivorous pitcher.

pla·gi·o·tro·pic (pla´djē ō trop´ik) adj. of growth, branching away from the vertical, towards the side; oblique. [< Gk. plagios πλάγιος slanting (< plagos πλάγος side) + tropos τρόπος a turn toward + -ikos -ικος relating to] —pla´gi·o·trop´i·cal·ly, adv.

pla·gi·o·tro·pism (pla´djē ō trō´piz əm) n. the growth upwards and laterally, but away from the vertical. [< Gk. plagios πλάγιος slanting (< plagos πλάγος side) + tropē τροπῇ a turning + -ismos -ισμος state or condition]

plank·ter (plangk´ter) n. any organism which exists as a component of the plankton. [< Gk. planktḗr πλανκτήρ roamer]

plank·ton (plangk´tən) n. the aggregate collection of organisms which exist by passively drifting or by being somewhat motile, in the water column of a large body such as an ocean or lake. Most are small or microscopic algae and protozoa, or their propagules. [< G < Gk. planktós πλανκτόs drifting] —plank·ton´ic, adj.

plantation hardwood n. the wood of the Pará rubber tree (Hevea brasiliensis (Willd. ex A.Juss.) Müll.Arg., of the Euphorbiaceae), suitable for various types of woodwork if treated for protection from fungi and insect-borers; parawood; Malaysian oak; rubberwood. It is eco-friendly because harvested from sustainable plantations.

pleu·ro·carp (plu̇´rō kärp´) n. a moss whose antheridium or archegonium is borne upon a lateral branch, rather than apically. [NL < Gk. pleuron πλευρόν the side + karpos καρπος fruit] —pleu´ro·car´pic, adj. —pleu´ro·car´pous, adj.

ploughman’s-spikenard n. an upright herb of grasslands and copses on calcareous soil (Inula conyza (Griess.) DC., of the Asteraceae), native to Europe and northern Asia; cinnamon root; great fleabane. It has been used in decoction for treatment of wounds, bruises, and inner pains.

ply·wood (plī´wu̇d) n. a type of wooden sheet used in construction, and formed by pressing and gluing alternating veneers of softwood together at right angles to each other.

pod·ded (pä´dəd) adj. 1 bearing pods; leguminous. 2 growing (as a seed) within a pod.

pod·der (pä´dėr) n. one who harvests peas within their pods; pease-cod gatherer. [< E pod + -er one who performs a specified action]

po·do·car·pa·ceous (pō´dō kar pā´shəs) adj. 1 of or pertaining to representatives of genus Podocarpus L’Hér. ex Pers., or of familia Podocarpaceae. 2 of or pertaining to fruit stipes. [< Gk. pous, podos πούς, ποδός foot + karpos καρπος fruit + L -aceus of or pertaining to, and/or adjectival correspondent to familia name]

po·do·car·pous (pō´dō kar´pəs) adj. of or pertaining to podocarps.

po·hu·tu·ka·wa (pä hü´tə kä´wä) n. an evergreen tree native to New Zealand (Metrosideros excelsa Sol. ex Gaertn., of the Myrtaceae), yielding a hard red wood, and bearing clusters of red flowers in Dec.-Jan.; Christmas tree. [Maori]

poi·ki·lo·hy·drous (poi´ki lō hī´drəs) adj. of plants, capable of opportunistic growth and desiccation tolerance. [< Gk. poikilos ποικίλος variation + hydro- ὕδρὁ water + L -osus full of, prone to] —poi´ki·lo·hy´dry, n.

poin·ci·an·a (pwän´sē an´ə) n. any of a number of bipinnate tropical trees which were previously congregated in the obsolete genus Poinciana L. (of the Fabaceae: Caesalpinioideae), and now in any of Delonix Raf., Caesalpinia L., or Peltophorum (Vogel) Benth. (all of the Fabaceae: Caesalpinioideae). They are usually distinguished by large, showy flowers, and are often cultivated for this characteristic. [< NL; named for Phillippe de Longvilliers de Poinci (1583-1660), governor of Saint Christophe]

poin·tel (pwän tel´ or poin´təl) n. 1 a pistil or style of a flower. 2 a stamen. [< OF < Ital. puntello, pontello bodkin, small point]

poin·trel (pwän´trəl or poin´trəl) n. 1 a pointed extremity upon the lobe of a leaf. 2 a pointel. [< OF pointe sharp end + -erel diminutive]

poire (pwäɾ) n. Cdn. saskatoon. [< Cdn.F poire sauvage wild pear]

poker plant n. tritoma.

po·lar·i·loc·u·lar (pō lar´i lok´yə lėr) adj. of a spore, exhibiting an extremely evident and wide equatorial septum perforated by a narrow channel, and thus possessing two distinct polar loculi. [< L polāris polar + loculāris kept in boxes]

pol·li·na·ri·um (pol´ə nār´ē əm) n. -ri·a. the complex structure existing in flowers of familia Apocynaceae, Asclepiadaceae, and Orchidaceae, to allow the attachment of 2 (or more) pollinia to an insect vector by translators and corpusculæ. [< L pollen mill dust + NL -arium locative suffix]

pol·y·cha·si·um (pol´i kā´zē əm) n. -si·a. a form of cymose inflorescence in which each main axis produces branches in numbers greater than two from each subapical node. The terminal flower is always the oldest. [< NL < Gk. polys πολύς many + chasis χάσις a separation + -ion -ιον locative suffix] —pol´y·cha´si·al, adj.

po·lym·er·ous (pə lim´ə rəs) adj. of whorled organs, being greater in number than their normal state. A flower having more than the usual number of petals or stamens in a whorl is said to be polymerous. [< Gk. polýmeros πολύμερος having many parts]

pol·y·pet·al·ous (pol´i pet´ə ləs) adj. of a taxon or its flowers, bearing separate distinct petals; choripetalous. [< Gk. polys πολύς many + petalon πέταλον leaf + L -ōsus prone to]

pol·y·ste·mo·nous (pol´ē ste´mə nəs) adj. of a taxon or its flowers, producing many – or numerous – stamens. [< Gk. polys πολύς many + stemōn στήμων thread, stamen + L -ōsus pertaining to, prone to]

pom-pom (päm´päm´) n. any variety of aster, chrysanthemum, or dahlia exhibiting an inflorescence which approaches a spherical mass with closely-packed florets. [< F pompon]

po·rous (pôr´əs) adj. 1 of tissue, possessing pores which allow for the absorption of fluids, such as water, or air. 2 usually of vascular tissue, displaying pores due to either of tracheids or xylem vessels. Wood may be said to be nonporous if pores are so tiny in cross-section as to appear absent, to be diffuse porous when pores are present but all of uniform size, and to be ring porous if the pores exhibit changes in size due to seasonal variation. [ME < OF poreux] —po·ros´i·ty, n. —po´rous·ness, n.

por·tiun·cle (pôr´shən kəl) n. Scot.obs. a small portion of land. [< F portioncule < L portiuncula small portion]

pot1 (pot) n. v.t. —n. a container, usually vaguely cylindrical or rounded, in which a plant or plants may be grown; flowerpot. Often fabricated of metal or plastic, such a container is optimally constructed of unglazed ceramic, which allows air exchange to the roots. —v.t. plant in a flowerpot, usually in a context of soil. [< OE pott < L potus drinking cup]

pot2 (pot) n. Slang. marijuana. [? < Mexican Sp. potiguaya marijuana leaves]

potato-apple n. the small fruit (a berry) of the potato plant.

potato-bean n. a dark brown excrescence which can grow upon the stem of a potato plant, reaching the size of a broad bean.

potato-scoop n. 1 a bladed tool which may be used for cutting portions from a potato tuber bearing eyes, for planting. 2 a grated shovel which allows the lifting of potatoes from the soil, while permitting the soil to fall back to the ground.

pot·herb (pät´(h)ėrb´) n. any herb grown for boiling in a pot: a black potherb is Smyrnium olusatrum L. (of the Apiaceae); alexanders. b white potherb is Valerianella locusta (L.) Laterr. (of the Valerianaceae); corn-salad; rapunzel.

pre·cur·sor (prē´kėr´sėr or pri kėr´sər) n. 1 a species or community which prevails before another, either in succession or in evolution (or both). 2 a cell or tissue which gives rise to a more complex or mature form. [ME < L præcursor forerunner] —pre·cur´so·ry, adj.

prick out cautiously remove an individual seedling from a seed tray, to a larger receptacle for continued growth.

pro·late (prō´lāt´) adj. of a spheroid, having the polar diameter being greater than the equatorial diameter. [NL < L prolatus carried forward, pp. of proferre prolong]

pro sp. Abbrev. a name previously applied as a specific epithet, but now applied solely to identify a hybrid. [L pro species before species]

pro spec. Abbrev. as described by, or as published under. [L pro species like the species]

pro·to·troph (prō´tə trōf´) n. 1 a microorganism which has the same nutritional requirements as those of the parent strain. 2 an organism or cell which is capable of manufacturing all of its metabolites from inorganic compounds; autotroph. [< Gk. prōtos πρῶτος first + trophos τροφός one who feeds] —pro´to·tro´phic, adj.

prov·e·nance (präv´ə nəns) n. of an organism, the origin or source. This may be expressed in geographical, palæontological, or genetic terms. [< F provenant < provenir come or stem from < L provenire < Gk. pro- πρό before + L venire come]

prox·i·mal (präk´si məl) adj. 1 in anatomy, situated closer to the place of attachment or origin. 2 nearby; proximate. [< L proximus nearest + -ālis pertaining to or belonging to] —prox´i·mal·ly, adv.

prox·i·mate (präk´si mət) adj. 1 nearby in space or in time. 2 the next or nearest in some system of ordering (e.g. phylogeny, cause-and-effect). [< LL proximātus drawn near] —prox´i·mate·ly, adv.

pseu·do·carp (sü´dō karp´) n. a false fruit, one which contains tissue in addition to the ovary and seeds; accessory fruit. [NL < Gk. pseudēs ψευδής false, deceptive + karpos καρπος fruit] —pseu´do·car´pous, adj.

pseu·do·drupe (sü´dō drüp´) n. a fruiting body characteristic of the genus Coriaria Niss. ex L. (of the Coriariaceae), in which the petals become succulent following fertilization and grow to enclose the 5-10 free carpels and their developing seeds. [NL < Gk. pseudēs ψευδής false, deceptive + dryppa δρύππα very ripe olive]

pseu·do·e·la·ter (sü´dō ē lā´tėr) n. among the genera of classis Anthocerotopsida, a multicellular strand of sterile cells among the spore tetrads in sporophytes, which may act to disperse the spores upon dehiscence. [NL < Gk. pseudēs ψευδής false, deceptive + elatēr ἐλατῆρ᾽ driver]

pun·gent (pun´jənt) adj. 1 of savour, having a biting or acrid taste or smell. 2 bearing a piercing or sharp point. [< L pungens pricking, piercing] —pun´gen·cy, n.

pun·net (pun´it) n. a small basket or other container for fruit, especially berries. [? dim. of dial. pun pound]

pussy toes or pussy-toes n. any of various herbal species, native to North America, of the genus Gnaphalium L. sect. Antennaria (Gaertn.) Baill. (of the Asteraceae), tomentose and distinguished by an inflorescence in which tegules are hirsute, although apically petaloid. This creates a lobed tomentose inflorescence which resembles the foot of a young cat.

pv. Abbrev. pathovar. [< NL pathovarietas]

pyc·nid·i·o·spore (pik nid´ē ō spôr´) n. a male nonmotile reproductive spore borne by certain Ascomycota and fungi imperfecti, including those in lichens, upon a pycnidium; spermatium. [NL < Gk. pyknos πυκνός compact, thick, dense + -idion -ΐδιον diminutive suffix + spora σπορά seed]

pyx·ie moss (pik´sē) n. an evergreen creeping shrub of New Jersey and the Carolinas of North America (Diapensia barbulata (Michx.) Elliott, of the Diapensiaceae), bearing tiny white flowers. [< NL Pyxidanthera Michx. (the former genus) < Gk. pyxídion πυξίδιον box + ánthera flowery]