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Term	Definition
Photosynthate	The carbohydrates produced by photosynthesis.
Photosynthesis	The process by which green plants produce carbohydrates from carbon dioxide and water utilizing radiant energy from the sun.
Photosynthetic bark	Refers to bark that harbors chlorophyll which gives at least some of the bark a green color. Most often plants with photosynthetic bark drop their leaves (are deciduous) at a certain time of year and whatever photosynthesis that takes place at that time is within the bark chlorophyll. Usually trees of species with photosynthetic bark grow under environmental stress at certain times of the year, e.g., during the dry season or when river levels rise and water covers the lower part of the trunk
Photosynthetic stems	Stems that harbor chlorophyll which gives them a green color. Often plants with photosynthetic stems drop their leaves (are deciduous) at a certain time of year and whatever photosynthesis that takes place at that time is within the stem chlorophyll. Usually plants with photosynthetic stems grow under environmental stress at certain times of the year, e.g., extremely dry periods during which considerable evapotranspiration would take place if the leaves were retained.
Phyllary (plural = phyllaries)	One of a series of overlapping bracts that subtends the capitulum (head) of Asteraceae.
Phylloclade	A branch that has taken on the form and function of a leaf.
Phyllode	A petiole and or rachis that has taken on the form and function of a leaf; e.g., in certain species of Acacia.
Pilose (diminutive = pilosulous)	A covering of long, soft, simple trichomes.
Pin flower	One of two types of flowers found in some species in which the style is long and the stamens are short. Compare with thrum flower; see heterostyly.
Pinnate	Feather-like; generally referring to the arrangement of veins along a midrib of a leaf blade or to leaflets along a rachis in a way that resembles the structure of a feather.
Pinnate (pinnately compound leaves)	Bearing leaflets along a common axis or rachis. See paripinnate and imparipinnate.
Pinnate venation	A type of venation pattern in which the secondary veins run parallel to each other from the midrib toward the margin.
Pinnately veined	Bearing the secondary veins along both sides and for the length of the midrib (primary vein).
Pinnule	A secondary or higher division of a compound leaf of ferns, in this example the marked pinnule is a primary pinnule which makes up the primary pinnule which, in turn, makes up the frond.
Pioneer	A species of plant that colonizes a deforested, barren, or disturbed area; e.g., many species of Cecropia (Cecropiaceae) are pioneer plants.
Pistil	The female part of the flower composed of the ovary, style, and stigma.
Pistillate flower	Referring to unisexual flowers with functional gynoecia but without functional stamens (staminodes may be present). Same as female flower.
Pistillate phase	Refers to species with bisexual flowers that release pollen and have receptive stigmas at different times over the course of floweirng, the pistillate phase is when the stigmas are receptive and the anthers either have or will release their pollen. This serves as a mechanism that promotes outcrossing, especially when the different phases are synchronous on the same plant.
Pith	The spongy ground tissue occupying the center of many stems.
Placenta (pl. = placentae)	The tissue within an ovary to which the ovules are attached or closely associated.
Placenta (plural = placentae)	The structure in the ovary to which the ovules are attached.
Placenta arched	A type of placentation in which the placenta arches from the top of the lower septum and gets progressively thicker toward the base as seen in medial longitudinal section.
Placenta columnar	A type of placentation in which the lower septum is only slightly expanded more-or-less equally throughout its length as seen in a medial longitudinal section.
Placenta flabellate	A type of placenta in which the ovules are inserted on placenta tissue that fans outward from the lower septum as viewed in medial longitudinal section.
Placenta incipient	A type of placenta which is barely expanded from the septum as seen in medial longitudinal section.
Placenta laminar	A placentation type in which the ovules are attached to laminae that run vertically through much of the ovary as seen in medial longitudinal section.
Placenta oblique	A type of placentation in which the placenta is derived from a short, horizontally expanded lower septum that expands at a right angle to the upper septum and may be slightly upward and outward oriented at its end as seen in medial longitudinal section.
Placental unit	The smallest continuous part of the placenta to which ovules are attached.
Placentation	In broadest terms, the arrangement of ovules within the ovary. See axile, basal, free-central, and parietal placentation.
Placentation	In broadest terms, the arrangement of ovules within the ovary. The most basic type of placentation classifies species as having parietal, axile, or free-central placentation.
Placentation basal	A type of placentation in which the ovule is attached to the floor of the locule.
Placentation bilamellar	A type of placentation that runs the length of the locule with two rows of ovules attached to two lamellae.
Placentation free-central	A type of placentation in which the ovules are borne on a central column arising from the base of a unilocular ovary.
Plane	Referring to a structure that is flat, even, or level with the surface of the structure in which it occurs; i.e., without projectiing above the surface of an organ.
Plank buttress	A flattened, board-like buttress.
Plant holder for photography	Devices, such as those shown here, can be used to secure plants in fixed positions to make it easy to photograph them. Note that the alligator clamp at the end of a flexible wire can either be attached to a branch or the base can be coiled into a circle and the device placed on the ground or another object. For more information about plant collecting see Tropical Plant Collecting: From the Filed to the Internet. This book can be purchased at: http://tecceditora.com/ or Amazon.com.
Plant holders for photography	Devices used to hold specimens of Lecythidaceae in place for photography.
Plant succesion	The sequence of plant communities that follows after natural or human disturbance.
Pleionanthy (pleionanthic, pleionanthous)	Referring to plants that flower repeatedly; i.e., those that do not die after a single flowering. Same as polycarpous and iteroparous; opposite of hapaxanthic and monocarpic.
Plinervada	Se refiere a una disposición de los nervios en las hojas, en la que el nervio medio o principal está longitudinalmente acompanado por varios otros nervios secundarios similares que nacen en la base de la hoja o cerca de ésta; por ejemplo, en muchas Ericaceae o algunas Euforbiaceae
Pliveined (plinerved)	Referring to leaf blade venation in which the midvein is accompanied by several nearly equal secondary veins arising at or near the base; e.g., in many Ericaceae and some Euphorbiaceae.
Plumose	Feathery or bearing featherlike hairs or bristles.
Pneumatophore	An erect, aerial breathing root found in species of wet habitats such as mangrove swamps.
Pneumatophore	An erect, aerial breathing root found in species of wet habitats such as mangrove swamps and along periodically inundated river banks.
Pock marks	A non technical term used to describe small circular depressions on the external surface of bark.
Pod	The most common fruit of the Fabaceae; see legume.
Polar nuclei	Two nuclei that migrate to the center of the embryo sac and fuse with a male nucleus (sperm) to form the primary endosperm nucleus which divides and sometimes forms the endosperm.
Pollen	Male reproductive structures contained within the anther of the stamen and usually released at anthesis. Same as microgametophytes.
Pollen drop	A small drop of liquid similar to nectar that accumulates on the apex of the ovule of gymnosperms. The wind-dispersed pollen of gymnosperms lands on the pollination drop and when it dries the pollen is carried into the ovule where it eventually fertilizes the egg to produce an embryo. See A in the attached figure.
Pollen guide	Markings on a flower that apparently serve to guide pollinators to pollen which is the reward they receive from the flower. Some are visible to humans, but others are apparent to humans only through ultraviolet photography.

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