A raceme ( or ) or racemoid is an unbranched,

indeterminate Indeterminate may refer to: In mathematics * Indeterminate (variable), a symbol that is treated as a variable * Indeterminate system, a system of simultaneous equations that has more than one solution * Indeterminate equation, an equation that ha ...

type of

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed ...

bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the shoot grows in height, with no predetermined growth limit. Examples of racemes occur on mustard (

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

Brassica ''Brassica'' () is a genus of plants in the cabbage and mustard family (Brassicaceae). The members of the genus are informally known as cruciferous vegetables, cabbages, or mustard plants. Crops from this genus are sometimes called ''cole ...

'') and radish (genus '' Raphanus'') plants.

Definition

A ''raceme'' or ''racemoid'' is an unbranched,

type of

bearing pedicellate

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...

s (flowers having short floral stalks called '' pedicels'') along its axis. In

botany Botany, also called plant science (or plant sciences), plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "bot ...

, an ''axis'' means a shoot, in this case one bearing the flowers. In indeterminate inflorescence-like racemes, the oldest flowers grow close to the base and new flowers are produced as the shoot grows in height, with no predetermined growth limit. A plant that flowers on a showy raceme may have this reflected in its scientific name, e.g. the

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

'' Cimicifuga racemosa''. A compound raceme, also called a

panicle A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit In botany, a fruit is the seed-bearing structure in flowering plants that is ...

, has a branching main axis. Examples of racemes occur on mustard (

'') and radish (genus '' Raphanus'') plants.

Spike

A spike is an unbranched, indeterminate inflorescence, similar to a raceme, but bearing sessile flowers (sessile flowers are attached directly, without stalks). Examples occur on Malabar nut ('' Justicia adhatoda'') and chaff flowers (genus ''

Achyranthes ''Achyranthes'' is a genus of medicinal and ornamental plants in the amaranth family, Amaranthaceae. Chaff flower is a common name for plants in this genus. Species include: * '' Achyranthes ancistrophora'' C.C.Towns. * '' Achyranthes arboresce ...

''). A spikelet can refer to a small spike, although it primarily refers to the ultimate flower cluster unit in grasses ( family Poaceae) and sedges (family

Cyperaceae The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus '' Carex'' ...

), in which case the stalk supporting the cluster becomes the pedicel. A true spikelet comprises one or more florets enclosed by two

glume In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grasses (Poaceae) or the flowers of sedges (Cyperaceae). There are two other types of bracts in the spikelets of grasses: the lemma ...

s (sterile bracts), with flowers and glumes arranged in two opposite rows along the spikelet. Examples occur on rice (species '' Oryza sativa'') and wheat (genus ''

Triticum Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

''), both grasses.

Catkin

An ament or catkin is very similar to a spike or raceme "but with subtending bracts so conspicuous as to conceal the flowers until pollination, as in the pussy–willow,

alder Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...

, nd

birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' contains 3 ...

...". These are sometimes called ''amentaceous plants''.

Spadix

A spadix is a form of spike in which the florets are densely crowded along a fleshy axis and enclosed by one or more large, brightly–colored bracts called '' spathes''. Usually the female flowers grow at the base, and male flowers grow above. They are a characteristic of the family

Araceae The Araceae are a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe (or leaf-like bract). ...

, for example jack–in–the–pulpit (species ''

Arisaema triphyllum ''Arisaema triphyllum'', the jack-in-the-pulpit, bog onion, brown dragon or Indian turnip, is a herbaceous perennial plant growing from a corm. It is a highly variable species typically growing in height with three-part leaves and flowers con ...

'') and wild calla (genus '' Calla'').

Examples

File:Traube (inflorescence).svg, File:Inflorescences Spike Kwiatostan Kłos.svg, File:Kätzchen (inflorescence).svg, File:Kolben (inflorescence).svg, File:Spathoglottis flwrs reduced.jpg, The inflorescence of '' Spathoglottis plicata'', a

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowering ...

, is a typical raceme. File:Backlit xeronema flower raceme.jpg, Tightly packed raceme of '' Xeronema callistemon'', with prominent red

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

s File:Pycreus.jpg, Every radiating unit in this inflorescence of a ''

Cyperus ''Cyperus'' is a large genus of about 700 species of sedges, distributed throughout all continents in both tropical and temperate regions. Description They are annual or perennial plants, mostly aquatic and growing in still or slow-moving ...

'' sedge is a spikelet composed of small flowers (florets) arranged in two ranks.

Etymology

From classical Latin, a ''racemus'' is a cluster of grapes.Oxford English Dictionary. Raceme 2. Bot. A type of inflorescence in which the flowers are arranged on short, nearly equal, lateral pedicels, at equal distances along a single elongated axis

References

{{Authority control Flowers Plant morphology sv:Blomställning#Typer av blomställningar