tetrad axis

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• Disphenoid — The tetragonal and digonal disphenoids can be positioned inside a cuboid bisecting two opposite faces. All four faces are isosceles triangles. Both have four equal edges going around the sides. The digonal has two sets of isosceles triangle faces …   Wikipedia

• plant — plantable, adj. plantless, adj. plantlike, adj. /plant, plahnt/, n. 1. any member of the kingdom Plantae, comprising multicellular organisms that typically produce their own food from inorganic matter by the process of photosynthesis and that… …   Universalium

• Glossary of botanical terms — Many of the terms used in Wikipedia glossaries (often most) are already defined and explained within Wikipedia itself. However, lists like the following indicate where new articles need to be written and are also useful for looking up and… …   Wikipedia

• angiosperm — /an jee euh sperrm /, n. Bot. a plant having its seeds enclosed in an ovary; a flowering plant. Cf. gymnosperm. [ANGIO + SPERM] * * * ▪ plant Introduction       any member of the more than 300,000 species of flowering plants (division Anthophyta) …   Universalium

• fern — fernless, adj. fernlike, adj. /ferrn/, n. any seedless, nonflowering vascular plant of the class Filicinae, of tropical to temperate regions, characterized by true roots produced from a rhizome, triangular fronds that uncoil upward and have a… …   Universalium

• Fern — /ferrn/, n. a female given name. * * * Any of about 10,000–12,000 species (division Filicophyta) of nonflowering vascular plants that have true roots, stems, and complex leaves and reproduce by spores. Though ferns were once classified with the… …   Universalium

• Frame fields in general relativity — In general relativity, a frame field (also called a tetrad or vierbein) is a set of four orthonormal vector fields, one timelike and three spacelike, defined on a Lorentzian manifold that is physically interpreted as a model of spacetime. The… …   Wikipedia

• Evolutionary history of plants — Plants have evolved through increasing levels of complexity, from the earliest algal mats, through bryophytes, lycopods, ferns and gymnosperms to the complex angiosperms of today. While the simple plants continue to thrive, especially in the… …   Wikipedia

• reproductive system, plant — Introduction       any of the systems, sexual or asexual, by which plants reproduce. In plants, as in animals, the end result of reproduction is the continuation of a given species, and the ability to reproduce is, therefore, rather conservative …   Universalium

• Crystal structure — In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice… …   Wikipedia

• Lorentz group — Group theory Group theory …   Wikipedia