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Placenta laminar
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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. |
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Placenta oblique
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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. |
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Placental unit
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The smallest continuous part of the placenta to which ovules are attached. |
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Placentation
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In broadest terms, the arrangement of ovules within the ovary. See axile, basal, free-central, and parietal placentation. |
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Placentation
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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. |
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Placentation basal
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A type of placentation in which the ovule is attached to the floor of the locule. |
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Placentation bilamellar
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A type of placentation that runs the length of the locule with two rows of ovules attached to two lamellae. |
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Placentation free-central
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A type of placentation in which the ovules are borne on a central column arising from the base of a unilocular ovary. |
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Plane
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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. |
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Plank buttress
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A flattened, board-like buttress. |
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Plant holder for photography
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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. |
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Plant holders for photography
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Devices used to hold specimens of Lecythidaceae in place for photography. |
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Plant succesion
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The sequence of plant communities that follows after natural or human disturbance. |
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Pleionanthy (pleionanthic, pleionanthous)
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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. |
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Plinervada
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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 |
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Pliveined (plinerved)
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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. |
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Plumose
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Feathery or bearing featherlike hairs or bristles. |
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Pneumatophore
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An erect, aerial breathing root found in species of wet habitats such as mangrove swamps. |
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Pneumatophore
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An erect, aerial breathing root found in species of wet habitats such as mangrove swamps and along periodically inundated river banks. |
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Pock marks
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A non technical term used to describe small circular depressions on the external surface of bark. |
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Pod
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The most common fruit of the Fabaceae; see legume. |
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Polar nuclei
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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. |
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Pollen
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Male reproductive structures contained within the anther of the stamen and usually released at anthesis. Same as microgametophytes. |
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Pollen drop
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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. |
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Pollen guide
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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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