Home to the plants of the Sonoran, Chihuahuan and Mojave Deserts
The botanical glossary used in Southwest Desert Flora is an alphabetical list of words or terms relevant to the descriptions here. In addition to the more difficult or unusual words defined here the glossary also provides definitions to some of the more common day-to-day botanical words that are not necessarily understood by all readers. This glossary is regularly updated or modified.
Regular; radially symmetrical; may be bisected into similar halves in at least two planes. Applies e.g. to steles and flowers in which the perianth segments within each whorl are alike in size and shape; compare Regular; contrast with Asymmetrical, Irregular, Zygomorphic.
A fan or cone-shaped deposit of granular fertile soil deposited by streams or other drainage from mountainous terrain. The formation of one or more alluvial fans into a single fan against a slope is called a bajada (see Bajada).
Leaves or flowers borne singly at different levels along a stem includes spiralled parts; or (as preposition) when something occurs between something else, for example stamens alternating with petals; compare Opposite
1. (of a flower) the period during which pollen is presented and/or the stigma is receptive.
2. (of a flowering plant) the period during which flowers in anthesis are present. note: not defined for some cases, such as when pollen is released in the bud.
An alluvial fan of deposits of sediment by a stream settling onto flats at the front of a mountain. Derived from the Spanish word bajada; meaning with a sense of “descent” or “inclination” (see Alluvial fan).
Falling off early, for example the sepals of poppies, that fall off when the petals begin to open; compare Persistent and Fugacious.
A soil type rich in calcium carbonate (CaCO3). Southwestern calcareous soils contain heavy amounts of limestone and lime. (see Caliche and Limestone.
A hardened natural cement of calcium carbonate (CaCO3) that binds other materials—such as gravel, sand, clay, and silt. It is generally light-colored and occurs in arid or semi-arid regions in the Sonoran and Mojave Deserts. The term caliche is Spanish originally from the Latin calx, meaning lime. see Calcareous and Limestone.
(adj. calyculate) (calyculi) (1) a cup-shaped structure formed from bracts, (2) in some Asteraceae, an extra set of bracts or phyllaries just below the involucre simulating a calyx; an involucel.
(Plural calyces) the outer whorl of a flower, usually green; the sepals of one flower collectively.
A tube formed by the fusion of the sepals (calyx), at least at the base.
Approaching white in color, covered with dense white (or grayish-white tricomes) down or wool.
A dense cluster of sessile, or almost sessile, flowers or florets; a head.
A dry fruit formed from two of more united carpels and dehiscing when ripe (usually by splitting into pieces or opening at summit by teeth or pores).
The basic female reproductive organ in flowering plants.
A spike, usually pendulous, in which the mostly small flowers are unisexual and without a conspicuous perianth; e.g. willows, poplars, oaks and casuarinas. The individual flowers often have scaly bracts; they are generally wind-pollinated. The catkins are usually shed as a unit.
Caudex (plural: caudices)
Literally the stem of a plant, but also used to mean a rootstock, or particularly a basal stem structure or storage organ from which new growth arises. See also Connate
Literally meaning "stem-like" or "caudex-like", is sometimes used to mean "pachycaul", meaning "thick-stemmed". See also Caudex
Fleshy, swollen stem base, usually underground, storing food reserves, with buds naked or covered by very thin scales; a type of rootstock. Adjectives derived from "corm" include "cormose" and "cormous";.
(adjective: coronate) literally, crown
1. in flowering plants, ring of structures that may be united in a tube, arising from the corolla or perianth of a flower and standing between the perianth lobes and the stamens. The trumpet of a daffodil is a corona.
2. in grasses, a hardened ring of tissue surmounting the lemma in some species.
The term cultivar is derived from cultivated variety and denotes an assemblage of cultivated plants clearly distinguished by one or more characters (morphological, physiological, cytological, chemical or other); when reproduced (sexually or asexually), the assemblage retains its distinguishing characters. A cultivar may arise in cultivation or be introduced from the wild. It is a variant of horticultural interest or value. Cultivar names are written with single quotation marks around them e.g. 'Blue Carpet', 'Alba'. All new names established after 1 January 1959, must be in common language (that is, not in Latin) but names established in Latin prior to this date are retained in Latin form.
Forking into two equal branches. This may result from an equal division of the growing tip, or may be sympodial, in which the growing tip is aborted and replaced. Typically refers to mode of branch growth, as in Aloe dichotoma, but also to other organs, such as the thorns of various species of Carissa (which morphologically are branches) and thalli or hyphae of various algae and fungi.
Resembling a disc or plate, having both thickness and parallel faces and with a rounded margin. Also used to describe the flower head of Compositae where there are no ray florets, but only disc florets.
Occurring in widely separated geographic areas, distinctly separate; applies to a discontinuous range in which one or more populations are separated from other potentially interbreeding populations far enough as to preclude gene flow between them.
Local extinction, or extirpation, is the condition of a species (or other taxon) that ceases to exist in the chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions.
Vascular plant without significant woody tissue above or at the ground. Forbs and herbs may be annual, biennial, or perennial but always lack significant thickening by secondary woody growth and have perennating buds borne at or below the ground surface.
A seed-bearing plant with unenclosed ovules borne on the surface of a sporophyll; includes, among others, conifers, Ginkgo, Gnetum and cycads. From gymno = naked, exposed; compare angio = covered, enclosed.
Native to the area; its presence in that region is the result of only natural processes with no human intervention; not introduced and not necessarily confined to the region discussed (hardly distinct from ‘native’ but usually applied to a smaller area). The term is equivalent to "native" in less scientific usage. For example, the Joshua Tree (Yucca brevifolia) is native to parts of the southwest but indigenous to Joshua National Park, California. Compare; Endemic; Native.
A structure surrounding or supporting, usually a head of flowers. In Asteraceae, it is the group of phyllaries (bracts) surrounding the inflorescence before opening, then supporting the cup-like receptacle on which the head of flowers sits. In Euphorbiaceae it is the cuplike structure that holds the nectar glands, nectar, and head of flowers, and sits above the bract-like cyathophyll structure.
Keystone species (A species with a disproportionately large effect on its natural environment relative to its abundance. A keystone species is a plant or animal that plays a unique and crucial role in the way an ecosystem functions.
A specimen chosen by a later researcher to serve as if it were the holotype (specimen designated in the original description). It is chosen from among the specimens available to the original publishing author (the isotypes, syntypes and/or paratypes) of a scientific name when the holotype was either lost or destroyed, or when no holotype was designated. Also see Holotype.
1. a fruit characteristic of the family Fabaceae, formed from one carpel and either dehiscent along both sides, or indehiscent.
2. a crop species in the family Fabaceae.
3. a plant belonging to the Fabaceae family).
1. Small membranous appendage on the top of the sheath of grass leaves.
2. A minute adaxial appendage near the base of a leaf, e.g. in Selaginella.
3. Extended, strap-like corolla of some daisy florets. See Ligulate.
A sedimentary rock (CaCO3), composed mostly of skeletal fragments of marine organisms such as coral, forams and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). see Calcareous Calcareous and Caliche Caliche.
Very narrow in relation to its length, with the sides mostly parallel.
Carl Linnaeus (1707-1778) was a Swedish botanist, zoologist and physician known as the “father of modern taxonomy” which is the modern system of classifying all organisms. Dr. Linnaeus has inspired and influenced many generations of biologists.
Marcescent refers to the retention of dead and dry elements that normally are shed on a living plant. A marcescent plant is therefore a plant that keeps some organs, most often leaves or flowers, after they die.
One segment of a fruit (a schizocarp) that splits at maturity into units derived from the individual carpels, or a carpel, usually 1-seeded, released by the break-up at maturity of a fruit formed from 2 or more joined carpels. (see Schizocarp).
Leaves or flowers borne at the same level but on opposite sides of the axis; or (as verb) when something occurs on the same radius as something else, for example anthers opposite sepals; compare Alternate.
1. leaf with veins radiating out from a central point (usually at the top of a petiole), resembling spread out fingers pointing away from the palm.
2. A compound palmate leaf has leaflets that radiate from a central point (usually at the top of a petiole).
A pedicel is a stem that attaches single flowers to the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower. The stem or branch from the main stem of the inflorescence that holds a group of pedicels is called a peduncle.
1. a legume, the fruit of a leguminous plant, a dry fruit of a single carpel, splitting along two sutures. 2. siliqua and silicula, the fruit of Brassicaceae, a dry fruit composed of two carpels separated by a partition.
(adjective: prickly) hard, pointed outgrowth from the surface of a plant (involving several layers of cells but not containing a vein); sharp outgrowth from the bark, detachable without tearing wood; cf. thorn.
(plural rachises; rachides) the axis of an inflorescence or a pinnate leaf; for example ferns; secondary rachis is the axis of a pinna in a bipinnate leaf distal to and including the lowermost pedicel attachment.
Leaf description, shaped like the head of an arrow; narrow and pointed but gradually enlarged at base into two straight lobes directed downwards; may refer only to the base of a leaf with such lobe; compare Hastate.
A fruit (seed capsule) of 2 fused carpels with the length less than three times the width. When the length is greater than three times the width of the dried fruit it is referred to as a silique; compare Silique.
A fruit (seed capsule) of 2 fused carpels with the length being more than three times the width. When the length is less than three times the width of the dried fruit it is referred to as a silicle; compare Silicle.
Part of a flower or perianth segment, either sepal or petal; usually used when the parts of the perianth are difficult to distinguish, e.g. the petals (caylx) and sepals (corolla) share the same color, or the petals are absent and the sepals are colorful.
Perennial, woody plant with a single stem (trunk), normally greater than 4 to 5 meters (13 to 16 feet) in height; under certain environmental conditions, some tree species may develop a multi-stemmed or short growth form (less than 4 meters or 13 feet in height). Applies to vascular plants only.
In non-filamentous plants, any hair-like outgrowth from epidermis, e.g. a hair or bristle; sometimes restricted to unbranched epidermal outgrowths.
(adjective umbellate) A racemose inflorescence in which all the individual flower stalks arise in a cluster at the top of the peduncle and are of about equal length; in a simple umbel, each stalk is unbranched and bears only one flower; a cymose umbel is an apparent umbel but its flowers open centrifugally.