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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. A flower, also known as a bloom or Blossom, is the reproductive structure found in Flowering plants (plants of the division Magnoliophyta, also A stem is one of two main structural axes of a Vascular plant. A branch ( American English ˈbræntʃ British English ˈbrɑːntʃ or tree branch (sometimes referred to in Botany as a ramus Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified. Shoots are new plant growth they can include stems, flowering stems with flower buds leaves The spermatophytes (from the Greek word "Σπερματόφυτα" (also known as phanerogams) comprise those Plants that produce Seeds They are A flower, also known as a bloom or Blossom, is the reproductive structure found in Flowering plants (plants of the division Magnoliophyta, also The modifications can involve the length and the nature of the internodes and the phyllotaxis, as well as variations in the proportions, compressions, swellings, adnations, connations and reduction of main and secondary axes. In Botany, phyllotaxis or phyllotaxy is the arrangement of the leaves on the stem of a Plant.

The stem holding the whole inflorescence is called a peduncle and the main stem holding the flowers or more branches within the inflorescence is called the rachis. The stalk of each single flower is called a pedicel.

The fruiting stage of an inflorescence is known as an infructescence. The term fruit has different meanings dependent on context and the term is not synonymous in Food preparation and Biology.

A flower that is not part of an inflorescence is called a solitary flower and its stalk is also referred to as a peduncle.

Contents

General characteristics

Inflorescences are described by many different characteristics including how the flowers are arranged on the peduncle, the blooming order of the flowers and how different clusters of flowers are grouped within it. These terms are general representations as plants in nature can have a combination of types.

Bracts

Inflorescences usually have modified foliage different from the vegetative part of the plant. Considering the broadest meaning of the term, any leaf associated with an inflorescence is called a bract . In Botany, a bract is a modified or specialized Leaf. Bracts are ordinarily associated with reproductive structures (subtending Flowers Inflorescence A bract is usually located at the node where the main stem of the inflorescence forms, joined to the main stem of the plant, but other bracts can exist within the inflorescence itself. They serve a variety of functions which include attracting pollinators and protecting young flowers. According to the presence or absence of bracts and their characteristics we can distinguish:

If many bracts are present and they are strictly connected to the stem, like in the family Asteraceae, the bracts might collectively be called an involucre. The family Asteraceae or Compositae (known as the aster, daisy, or sunflower family) is the largest family of Flowering If the inflorescence has a second unit of bracts further up the stem, they might be called an involucel.

Ebracteate inflorescence.

Ebracteate of Wisteria sinensis

Bracteate inflorescence. Wisteria sinensis ( Chinese Wisteria) is a woody, Deciduous, perennial climbing Vine in the genus Wisteria

Bracteate inflorescence of Pedicularis verticillata.

Leafy-bracted inflorescence.

Leafy-bracted inflorescence of Rhinanthus angustifolius. Rhinanthus angustifolius or Greater Yellow-rattle is a plant species of the genus Rhinanthus.

Leafy inflorescence.

Leafy inflorescence of Aristolochia clematitis. Aristolochia clematitis, (European Birthwort, is a Herbaceous plant in the Aristolochiaceae family which is native to Europe

Terminal flower

Plant organs can grow according to two different schemes, namely monopodial and sympodial. Vascular plants with monopodial growth habits grow upward from a single point Orchids with sympodial growth have a specialized lateral growth pattern in which the terminal Bud dies In inflorescences these two different growth patterns are called indeterminate or determinate, and indicate whether a terminal flower is formed and where flowering starts within the inflorescence.

Indeterminate and determinate inflorescences are sometimes referred to as open and closed inflorescences respectively.

In determinate inflorescences the terminal flower is usually the first to mature (praecursive development), while the others tend to mature starting from the bottom of the stem. This pattern is called acropetal maturation. When flowers start to mature from the top of the stem , maturation is basipetal, while when the central mature first, divergent.

Determinate inflorescence with acropetal maturation

Determinate inflorescence with basipetal maturation

Determinate inflorescence with divergent maturation

In indeterminate inflorescence there is no true terminal flower and the stem usually has a rudimentary end. In many cases the last true flower formed by the terminal bud (subterminal flower) straightens up, appearing to be a terminal flower. Often a vestige of the terminal bud may be noticed higher on the stem.

Indeterminate inflorescence with a perfect acropetal maturation.

Indeterminate inflorescence with a acropetal maturation and lateral flower buds.

Indeterminate inflorescence with the subterminal flower to simulate the terminal one (vestige present)

Phyllotaxis

As with leaves, flowers can be arranged on the stem according to many different patterns. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. See 'Phyllotaxis' for in-depth descriptions. In Botany, phyllotaxis or phyllotaxy is the arrangement of the leaves on the stem of a Plant.

Alternate flowers

Opposite flowers

Metatopy

When a single flower or a cluster is located at the axil of a bract (which can be reduced), the location of the bract in relation to the stem holding the flower(s) is indicated by the use of different terms and may be a useful diagnostic indicator.

Flower and subtending bract

Lilium martagon (flower and subtending bract)

Concaulescence

Solanum lycopersicum (concaulescence)

Recaulescence

Tilia cordata (recaulescence)

Organisation

There is no general consensus in defining the different inflorescences. Lilium martagon ( Martagon or Turk's cap lily) is a species of lily. The tomato ( Solanum lycopersicum, syn Lycopersicon lycopersicum) is a herbaceous usually sprawling plant in the Solanaceae or nightshade family Tilia cordata ( Small-leaved Lime, occasionally Small-leaved Linden is a species of Tilia native to much of Europe and western The following is based on Focko Weberling's Morphologie der Blüten und der Blütenstände (Stuttgart, 1981).

The main groups of inflorescences are distinguished by branching. Within these groups, the most important characteristics are the intersection of the axes and different variations of the model.

Inflorescences can be simple or compound.

Simple inflorescences

Indeterminate simple inflorescences are generally called racemose. The main kind of racemose inflorescence is the raceme, the other kind of racemose inflorescences can all be derived from this one by dilation, compression, swelling or reduction of the different axes. Some passage forms between the obvious ones are commonly admitted.

Raceme

Epilobium angustifolium

Spike

Plantago media (spike)

Racemose corymb

Iberis umbellata (racemose corymb)

Umbel

Astrantia minor (umbel)

Spadix

Arum maculatum (spadix)

Head (round)

Dipsacus fullonum (head)

Catkin (racemose or spicate)

Alnus incana (ament)

Determinate simple inflorescences are generally called cymose. A raceme is a type of Inflorescence that is unbranched and indeterminate and bears pedicellate Flowers &mdash flowers having short Fireweed or (mainly in Britain) Rosebay Willowherb ( Epilobium angustifolium) is a perennial Herbaceous Plant in the willowherb Plantago media, known as the hoary plantain, is a species of genus Plantago native to central Europe and introduced to parts of the north-east A panicle is a compound Raceme, a loose much-branched indeterminate Inflorescence with pedicellate Flowers (and Fruit An umbel is an Inflorescence which consists of a number of short Flower stalks (called pedicels) which are equal in length and spread from a common In Botany, a spadix (pl spadices) is a type of spike: an Inflorescence with small Flowers crowded on a thickened fleshy axis Arum maculatum is a common woodland plant Species of the Araceae family Dipsacus is a Genus of Flowering plant in the family Dipsacaceae. A catkin or ament is a slim cylindrical flower cluster with inconspicuous or no petals usually Wind - pollinated ( anemophilous) but sometimes Alnus incana ( Grey or Speckled Alder) is a species of Alder with a wide range across the cooler parts of the Northern Hemisphere The main kind of cymose inflorescence is the cyme. Cymes are further divided according to this scheme:

Although it is commonly said to be a scorpioid cyme, the typical inflorescence of the family Boraginaceae is in fact the cincinnus, a helicoid cyme. Boraginaceae Juss 1789 the Borage or Forget-me-not family includes a variety of Shrubs Trees and Herbs totaling about 2000 species Iridaceae is a family of plants in Order Asparagales, taking its name from the Irises. The Caryophyllaceae, commonly called the pink family or carnation family, is a family of Flowering plants The species are Dicotyledons Boraginaceae Juss 1789 the Borage or Forget-me-not family includes a variety of Shrubs Trees and Herbs totaling about 2000 species

Dichasium

Dichasium, top view

Silene dioica (dichasium)

Double cyme

Double cyme

Cincinnus (lateral and top view)

Symphytum officinale (cincinnus)

Bostryx (lateral and top view)

Hypericum perforatum (bostryx)

Rhipidium (lateral and top view)

Canna sp. Red campion ( Silene dioica, syn Melandrium rubrum) is a Flowering plant in the family Caryophyllaceae, native throughout Symphytum officinale is a Perennial Flowering plant of the genus Symphytum in the family Boraginaceae. St John's wort (pronounced) used alone refers to the species Hypericum perforatum, also known as Tipton's Weed or Klamath weed, but with qualifiers is (rhipidium)

Drepanium (lateral and top view)

Gladiolus imbricatus (drepanium)

A cyme can also be so compressed that it looks like an umbel. Strictly speaking this kind of inflorescence could be called umbelliform cyme, although it is normally called simply 'umbel'.

Another kind of definite simple inflorescence is the raceme-like cyme or botryoid; that is as a raceme with a terminal flower and is usually improperly called 'raceme'.

Umbelliform cyme

Pelargonium zonale (umbelliform cyme)

Botryoid

Berberis vernae (botryoid)

A reduced raceme or cyme that grows in the axil of a bract is called a fascicle. Pelargonium is a Genus of Flowering plants which includes about 200 Species of perennial, succulent, and Shrub A verticillaster is a fascicle with the structure of a dichasium; it is common among the Lamiaceae. Lamiaceae or Labiatae, also known as the mint family is a family of Plants comprising about 210 genera and some 3500 species Many verticillasters with reduced bracts can form a spicate (spike-like) inflorescence that is commonly called a spike.

Gentiana lutea (fascicles)

Lamium orvala (verticillaster)

Mentha longifolia ('spike')

Compound inflorescences

Simple inflorescences are the basis for compound inflorescences or synflorescences. Gentiana lutea ( Great Yellow Gentian) is a species of Gentian native to the Mountains of central and southern Europe. Mentha longifolia ( Horse Mint; syn M spicata var longifolia L The single flowers are there replaced by a simple inflorescence, which can be both a racemose or a cymose one. Compound inflorescences are composed of branched stems and can involve complicated arrangements that are difficult to trace back to the main branch.

A kind of compound inflorescence is the double inflorescence, in which the basic structure is repeated in the place of single florets. For example a double raceme is a raceme in which the single flowers are replaced by other simple racemes; the same structure can be repeated to form triple or more complex structures.

Compound raceme inflorescences can either end with a final raceme (homoeothetic), or not (heterothetic). A compound raceme is often called a panicle. Note that this definition is very different from that given by Weberling.

Compound umbles are umbels in which the single flowers are replaced by many smaller umbles called umbellets. The stem attaching the side umbellets to the main stem is called a ray.

Homeothetic compound raceme

Melilotus officinalis (homoeothetic compound raceme)

Heterothetic compound raceme

Hebe albicans (heterothetic compound raceme)

Compound spike

Lolium temulentum (compound spike)

Compound capitulum

Echinops ritro (compound capitulum)

Compound (double) umbel

Laserpicium latifolium (double umbel)

Compound (triple) umbel

The most common kind of definite compound inflorescence is the panicle (of Webeling, or 'panicle-like cyme'). Yellow Sweet Clover ( Melilotus officinalis) also known as Yellow Melilot, is a Legume sometimes grown for forage. Lolium temulentum, typically known as darnel or cockle, is an annual plant that forms part of the Poaceae family and part of the Lolium Echinops ritro is a species of globe thistle. It is native to Europe and western Asia. A panicle is a definite inflorescence that is increasingly more strongly and irregularly branched from the top to the bottom and where each braching has a terminal flower.

The so called cymose corymb is similar to a racemose corymb but has a panicle-like structure. Another type of panicle is the anthela. An anthela is a cymose corymb with the lateral flowers higher than the central ones.

Panicle

Vitis vinifera (panicle)

Cymose corymb

Sambucus nigra (cymose corymb)

Anthela

Juncus inflexus (anthela)

A raceme in which the single flowers are replaced by cymes is called a (indefinite) thyrse. A panicle is a compound Raceme, a loose much-branched indeterminate Inflorescence with pedicellate Flowers (and Fruit Vitis vinifera ( Common Grape Vine) is a species of Vitis, native to the Mediterranean region, central Europe, and A panicle is a compound Raceme, a loose much-branched indeterminate Inflorescence with pedicellate Flowers (and Fruit Sambucus nigra is a species of elder native to most of Europe, northwest Africa and southwest Asia. The secondary cymes can of course be of any of the different types of dichasia and monochasia. A botryoid in which the single flowers are replaced by cymes is a definite thyrse or thyrsoid. Thyrses are often confusingly called panicles.

Thyrse

Aesculus hippocastanum

Thyrsoid

Syringa vulgaris

Other combinations are, of course, possible. Aesculus hippocastanum is a large Deciduous Tree, commonly known as Horse-chestnut or Conker tree. Syringa vulgaris ( Lilac or Common Lilac) is a species of Syringa in the olive family Oleaceae, native to the For example, heads or umbels may be arranged in a corymb or a panicle.

Achillea sp. Achillea is a genus of about 85 Flowering plants in the family Asteraceae, commonly referred to as yarrow. (heads in a corymb)

Hedera helix (umbels in a panicle)

Other

The family Asteraceae is characterised by a highly specialised head technically called a calathid (but usually referred to as 'capitulum' or 'head'). Hedera helix (species name from Ancient Greek "twist turn" also called Ivy, Common Ivy, or English Ivy is a species The family Asteraceae or Compositae (known as the aster, daisy, or sunflower family) is the largest family of Flowering The family Poaceae has a peculiar inflorescence of small spikes (spikelets) organised in panicles or spikes that are usually simply and improperly referred to as spike and panicle. Poaceae or Gramineae is a family in the Class Liliopsida of the flowering plants. The genus Ficus (Moraceae) has an inflorescence called syconium and the genus Euphorbia has cyathia (sing. Ficus is a Genus of about 850 Species of woody Trees Shrubs Vines Epiphytes and hemi-epiphytes in the family Moraceae is a family of Flowering plants commonly known as the mulberry or fig family An accessory fruit, false fruit, spurious fruit, epigynous fruit, syconium or pseudocarp is a Fruit where the fleshy Euphorbia is a Genus of Plants belonging to the family Euphorbiaceae. The very special pseudanthia in the genus Euphorbia ( Euphorbiaceae) are known as Cyathia. cyathium), usually organised in umbels. For detailed descriptions, see the respective articles.

Matricaria chamomilla (calathid)

Triticum aestivum (compound spikes, "spikes")

Oryza sativa (spikes in a panicle, "panicle")

Ficus carica (syconium)

Euphorbia tridentata (cyathium)

Euphorbia cyparissias (cyathia in an umbel)

References and external links

This article is based on a translation of an article from the German Wikipedia. Common wheat, Triticum aestivum, (also known as bread wheat) is a cultivated wheat species Rice is a Cereal foodstuff which forms an important part of the diet of many people worldwide and as such it is a staple food for many The Common fig ( Ficus carica) is a large Deciduous, Shrub or small Tree native to southwest Asia and the eastern Mediterranean Cypress Spurge is a plant in the genus Euphorbia, which is native to Europe and was introduced to North America in the 1860s by the colonists

Dictionary

inflorescence

-noun

  1. flower cluster
  2. (eventual etymological fallacy) a beginning to flower
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