3,306 articles
Pelargonium
Pelargonium (geraniums, stork's-bill genus), a Geraniaceae genus of ca. 280 species mostly from southern Africa, with zygomorphic nectar-spurred flowers, four subgenera, and horticulturally important scented species like P. graveolens.
Pelargonium graveolens
Pelargonium graveolens (rose geranium, rose-scented pelargonium) is a strongly aromatic southern African subshrub, Geraniaceae, source of rose geranium essential oil rich in citronellol and geraniol, used in perfumery, food, and traditional medicine.
Peltophorum
Peltophorum (Vogel) Benth., yellow-flowered trees of Fabaceae subfamily Caesalpinioideae, also called Baryxylum; seven accepted species, pantropical, sister to Bussea, used as ornamentals, timber, fodder, and medicine.
Penstemon
Penstemon (beardtongues), genus Penstemon Schmidel of Plantaginaceae, is the largest flowering-plant genus endemic to North America, with roughly 250–280 mostly western species, bee- and hummingbird-pollinated syndromes, and many rare edaphic endemics.
Pentadesma butyracea
Pentadesma butyracea (butter tree, tallow tree) is a West and Central African Clusiaceae tree up to 35 m whose seeds yield an edible butter rich in oleic and stearic acids, used in food, cosmetics, and traditional medicine.
Peony
Peony (Paeonia L.), sole genus of Paeoniaceae in Saxifragales, about 33-37 species of herbaceous and tree peonies native from Europe and temperate Asia to western North America; grown for ornament, traditional medicine (paeoniflorin, paeonol), and oil.
Peperomia
Peperomia (radiator plant) is a genus of over 1,300 species of often succulent Piperaceae herbs, native to tropics and subtropics, mostly tropical America, spanning C3 to CAM photosynthesis and popular as foliage houseplants.
Peppermint
Peppermint (Mentha × piperita) is a sterile hybrid mint, a cross between water mint and spearmint, grown for menthol-rich oil used in flavoring and medicine.
Perennial
Perennial: a plant living multiple years, regrowing from crown, rhizomes, or roots, unlike annuals. Covers herbaceous vs woody perennials, winter dormancy, garden care, and perennial grain crops such as Kernza.
Pericopsis elata
Pericopsis elata (afrormosia, African teak, kokrodua) is an endangered Fabaceae timber tree of West and Central African semi-deciduous forest, CITES Appendix II since 1992, traded as logs, sawn wood, and veneer.
Perilla frutescens
Perilla frutescens (shiso, Zisu, beefsteak plant), an East Asian mint-family herb grown as culinary herb and omega-3-rich oilseed; chemotypes differ in safety, with perilla ketone toxic to livestock.
Periploca
Periploca Tourn. ex L., a genus of 17 accepted species in Apocynaceae (Periplocoideae), native from Macaronesia and the Mediterranean to tropical Africa and Asia; includes medicinal species P. sepium (Xiangjiapi) and P. forrestii (Heiguteng).
Persea
Persea (laurel family, Lauraceae), genus of evergreen trees including the avocado Persea americana; about 112-150 species native to the Americas and Macaronesia, with Asian species often split off as Machilus; also yields medang timber.
Persicaria
Persicaria (knotweeds, smartweeds), a genus of about 100-150 species in Polygonaceae, cosmopolitan, split from Polygonum, recognized by ocrea and swollen nodes; includes weeds, ornamentals, and Asian mint.
Persicaria hydropiper
Persicaria hydropiper (water-pepper, marshpepper knotweed), Polygonaceae annual of wet ground, native temperate Eurasia, pungent from polygodial drimane sesquiterpenes; used as spice, medicine, poison; IUCN least concern.
Persicaria maculosa
Persicaria maculosa (spotted ladysthumb, redshank, lady's thumb; formerly Polygonum persicaria) is an annual Polygonaceae herb native to temperate Eurasia, a weed of spring crops with dark-blotched leaves and pink flower spikes, used as poison and medicine.
Persicaria odorata
Persicaria odorata, known as Vietnamese coriander or rau răm, is a perennial herb of the buckwheat family native to Southeast Asia, whose pungent, coriander-like leaves flavor laksa, salads, and laab.
Pescatoria
Pescatoria (also spelled Pescatorea) is a genus of 21 accepted neotropical orchid species in Zygopetalinae, Orchidaceae, native from Costa Rica to Ecuador; it absorbed Bollea and is a parent of the hybrid genus × Zygosepescalum.
Pests and diseases of cultivated orchids
Pests and diseases of cultivated orchids span roughly 30 viruses, fungi, water molds, bacteria, and pests; viral infections cannot be cured, so management relies on exclusion and sanitation.
Pests and diseases of yews and plum yews
Pests and diseases of yews and plum yews describes the main Taxus problems: Phytophthora root rot from poor drainage, black vine weevil, scales, and Cryptocline needle blight.
Petal
A petal is one of the sterile, often brightly colored floral organs that form the corolla inside the sepals, attracting pollinators by color, scent, and ultraviolet patterns.
Petasites
Petasites (butterbur), Asteraceae genus of rhizomatous Northern Hemisphere perennials with huge leaves; P. hybridus studied for migraine and allergic rhinitis; contains hepatotoxic pyrrolizidine alkaloids.
Petasites hybridus
Petasites hybridus (butterbur, pestilence wort) is an Asteraceae rhizomatous geophyte native from Europe to North Iran and Algeria, studied for migraine and hay fever, but toxic unless pyrrolizidine alkaloids are removed.
Petiole (botany)
In botany, a petiole, also called a leaf stalk, is the stalk attaching a leaf blade to the stem, carrying water, nutrients, and sugars between leaf and stem.
Petrea
Petrea is a genus of woody climbers and shrubs in the verbena family, native from Florida through tropical America, known for the wisteria-like queen's wreath vine.
Petrea volubilis
Petrea volubilis (queen's wreath, purple wreath, sandpaper vine) is a twining woody vine in Verbenaceae native to tropical America, grown ornamentally for wisteria-like racemes whose persistent pale calyx lobes outlast the darker corollas.
Peumus boldus
Peumus boldus (boldo) is a Monimiaceae tree endemic to central and southern Chile, source of boldo leaf herbal medicine and the alkaloid boldine, used traditionally for digestive disorders.
Peyote
Peyote (Lophophora williamsii) is a spineless mescaline-containing cactus of south Texas and northern Mexico, used ceremonially for over 5,000 years, sacred to the Native American Church, legally exempted for traditional Native American use, and listed as Vulnerable by the IUCN.
Phalaenopsis
Phalaenopsis, moth orchids, is an orchid genus established by Blume in 1825, native from tropical Asia to NE Australia, mainly epiphytic, and the most important orchid genus in cultivation.
Phalaris canariensis
Phalaris canariensis (canary grass, alpiste), annual Poaceae grass native to the Canary Islands and Morocco, grown mainly in Saskatchewan, Canada, for birdseed; glabrous grain approved for human food in 2016, gluten-free, 22% protein.