Bract

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Papery (upper) and leafy bracts on hay rattle (Rhinanthus minor). All the "leaves" in this image are bracts. Yellow-rattle close 700.jpg
Papery (upper) and leafy bracts on hay rattle ( Rhinanthus minor ). All the "leaves" in this image are bracts.

In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture. Typically, they also look different from the parts of the flower, such as the petals or sepals. A plant having bracts is referred to as bracteate [1] or bracteolate, while one that lacks them is referred to as ebracteate [2] and ebracteolate, without bracts.

Contents

Variants

Some bracts are brightly coloured and serve the function of attracting pollinators, either together with the perianth or instead of it. Examples of this type of bract include those of Euphorbia pulcherrima (poinsettia) and Bougainvillea : both of these have large colourful bracts surrounding much smaller, less colourful flowers. [3] [ citation needed ]

In grasses, each floret (flower) is enclosed in a pair of papery bracts, called the lemma (lower bract) and palea (upper bract), while each spikelet (group of florets) has a further pair of bracts at its base called glumes. These bracts form the chaff removed from cereal grain during threshing and winnowing. [4]

Bats may detect acoustic signals from dish-shaped bracts such as those of Marcgravia evenia . [5]

A prophyll is a leaf-like structure, such as a bracteole, subtending (extending under) a single flower or pedicel. The term can also mean the lower bract on a peduncle.

The frequently showy pair of bracts of Euphorbia species in subgenus Lacanthis are the cyathophylls.

Bracts subtend the cone scales in the seed cones of many conifers, and in some cases, such as Pseudotsuga , they extend beyond the cone scales.

Bracteole

A small bract is called a bracteole or bractlet. Technically this is any bract that arises on a pedicel instead of subtending it.

Involucral bracts

Beggar-tick (Bidens comosa) Leafy-bract-Beggar-ticks.we.jpg
Beggar-tick ( Bidens comosa )

Bracts that appear in a whorl subtending an inflorescence are collectively called an involucre. An involucre is a common feature beneath the inflorescences of many Apiaceae, Asteraceae, Dipsacaceae and Polygonaceae. Each flower in an inflorescence may have its own whorl of bracts, in this case called an involucel. In this case they may be called chaff, paleas, or receptacular bracts and are usually minute scales or bristles. Many asteraceous plants have bracts at the base of each inflorescence.[ citation needed ]

The term involucre is also used for a highly conspicuous bract or bract pair at the base of an inflorescence. In the family Betulaceae, notably in the genera Carpinus and Corylus , the involucre is a leafy structure that protects the developing nuts. Beggar-tick ( Bidens comosa ) has narrow involucral bracts surrounding each inflorescence, each of which also has a single bract below it. There is then a pair of leafy bracts on the main stem and below those a pair of leaves.[ citation needed ]

Epicalyx

Epicalyx of Hibiscus rosa-sinensis Hibiscus rosa-sinensis3 ies.jpg
Epicalyx of Hibiscus rosa-sinensis

An epicalyx, which forms an additional whorl around the calyx of a single flower, is a modification of bracteoles [6] In other words, the epicalyx is a group of bracts resembling a calyx or bracteoles forming a whorl outer to the calyx. [7] It is a calyx-like extra whorl of floral appendages. Each individual segment of the epicalyx is called an episepal because they resemble the sepals in them. [8] They are present in the hibiscus family, Malvaceae. Fragaria (strawberries) may or may not have an epicalyx.

Spathe

Anthurium scherzerianum inflorescence with spathe and spadix Anthurium scherzerianum 2.jpg
Anthurium scherzerianum inflorescence with spathe and spadix

A spathe is a large bract or pair of bracts forming a sheath to enclose the flower cluster of such plants as palms, arums, irises, [9] crocuses, [10] and dayflowers ( Commelina ). Zephyranthes tubispatha in the Amaryllidaceae derives its specific name from its tubular spathe. In many arums (family Araceae), the spathe is petal-like, attracting pollinators to the flowers arranged on a type of spike called a spadix.

Related Research Articles

<i>Euphorbia</i> Genus of flowering plants in the spurge family Euphorbiaceae

Euphorbia is a very large and diverse genus of flowering plants, commonly called spurge, in the family Euphorbiaceae. "Euphorbia" is sometimes used in ordinary English to collectively refer to all members of Euphorbiaceae, not just to members of the genus.

<span class="mw-page-title-main">Inflorescence</span> Term used in botany to describe a cluster of flowers

An inflorescence, in a flowering plant, is a group or cluster of flowers arranged on a stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a main axis (peduncle) and by the timing of its flowering.

<i>Commelina</i> Genus of flowering plants

Commelina is a genus of approximately 170 species commonly called dayflowers due to the short lives of their flowers. They are less often known as widow's tears. It is by far the largest genus of its family, Commelinaceae. The Swedish taxonomist Carl Linnaeus of the 18th century named the genus after the two Dutch botanists Jan Commelijn and his nephew Caspar, each representing one of the showy petals of Commelina communis.

<span class="mw-page-title-main">Spikelet</span> Part of a spike inflorescence of a grass or sedge

A spikelet, in botany, describes the typical arrangement of the flowers of grasses, sedges and some other monocots.

<span class="mw-page-title-main">Cyathium</span> A form of inflorescence of the type found on the poinsettia

A cyathium is one of the specialised pseudanthia forming the inflorescence of plants in the genus Euphorbia (Euphorbiaceae). A cyathium consists of:

This page provides a glossary of plant morphology. Botanists and other biologists who study plant morphology use a number of different terms to classify and identify plant organs and parts that can be observed using no more than a handheld magnifying lens. This page provides help in understanding the numerous other pages describing plants by their various taxa. The accompanying page—Plant morphology—provides an overview of the science of the external form of plants. There is also an alphabetical list: Glossary of botanical terms. In contrast, this page deals with botanical terms in a systematic manner, with some illustrations, and organized by plant anatomy and function in plant physiology.

Plectocomiopsis is a dioecious genus of flowering plant in the palm family found in Indochina, Malaysia, Borneo and Sumatra. Hapaxanthic and armed with spines, they are a climbing rattan, closely related to the Myrialepis palms. The name is Greek for "similar to Plectocomia", another close relative.

Pogonotium was a dioecious genus of flowering plant in the palm family found in Malaysia and Borneo. Its species are now included within the genus Calamus. Its close relatives are climbing rattans and while partially armed with climbing apparatus, its habit is sprawling and leaning but not effective climbing. The reduced inflorescence nestled between the auricles is unusual and distinguishes it from similar relatives like Calamus, Daemonorops and Ceratolobus. The name is Greek meaning "bearded".

Retispatha is a rare, monotypic genus of flowering plant in the palm family endemic to Borneo, where the sole species, Retispatha dumetosa, is known as wi tebu bruang or 'the bear's sugar cane'. The name combines Latin and Greek words meaning 'network' and 'spathe', and the species epithet means 'bushy'. While classified with other rattans, they retain only superficial climbing organs; they sprawl and lean but are not true climbers.

This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary of leaf morphology. For other related terms, see Glossary of phytopathology, Glossary of lichen terms, and List of Latin and Greek words commonly used in systematic names.

<i>Polyarrhena</i> Genus of plants

Polyarrhena is a genus of low, branching shrublets that is assigned to the daisy family. Its stems are alternately and densely set with entire or somewhat toothed leaves. Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and which are surrounded by an involucre of in this case three whorls of bracts. In Polyarrhena, the centre of the head is taken by yellow disc florets, and is surrounded by one single whorl of white ligulate florets that have a pinkish-purple wash on the underside. These florets sit on a common base and are not individually subtended by a bract. The species occur in the Cape Floristic Region. Polyarrhena reflexa has long been cultivated as an ornamental and is often known under its synonym Aster reflexum.

<i>Corymbium</i> Genus of perennial plants from South Africa

Corymbium is a genus of flowering plants in the daisy family comprising nine species. It is the only genus in the subfamily Corymbioideae and the tribe Corymbieae. The species have leaves with parallel veins, strongly reminiscent of monocots, in a rosette and compounded inflorescences may be compact or loosely composed racemes, panicles or corymbs. Remarkable for species in the daisy family, each flower head contains just one, bisexual, mauve, pink or white disc floret within a sheath consisting of just two large involucral bracts. The species are all endemic to the Cape Floristic Region of South Africa, where they are known as plampers.

<i>Stachys arvensis</i> Species of flowering plant

Stachys arvensis is a species of flowering plant in the mint family known by the common names field woundwort and staggerweed. It is native to Europe, Western Asia, and North Africa. It is known on other continents as an introduced species and widespread weed.

<span class="mw-page-title-main">Stifftioideae</span> Subfamily of flowering plants

The Stifftioideae are a subfamily of the family Asteraceae family of flowering plants. It comprises a single tribe, Stifftieae, of ten genera.

<i>Gorteria diffusa</i> Annual plant in the daisy family from South Africa

Gorteria diffusa is a highly variable, small annual herbaceous plant or rarely a shrublet that is assigned to the daisy family. Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and are surrounded by an involucre, consisting of in this case several whorls of bracts, which are merged at their base. In G. diffusa, the centre of the head is taken by relatively few male and bisexual yellow to orange disc florets, and is surrounded by one complete whorl of 5–14 infertile cream to dark orange ray florets, sometimes with a few ray florets nearer to the centre. None, some or all of them may have darker spots at their base. The fruits remain attached to their common base when ripe, and it is the entire head that breaks free from the plant. One or few seeds germinate inside the flower head which can be found at the foot of plants during their first year. The species flowers between August and October. It is called beetle daisy in English and katoog in Afrikaans. It can be found in Namibia and South Africa.

<i>Leucadendron salignum</i> Shrub in the family Proteaceae from the Cape provinces of South Africa

Leucadendron salignum, also known as the common sunshine conebush, is an evergreen, dioecious shrub that produces several stems from the ground of up to 2 metres high; forming part of the genus Leucadendron from the family Proteaceae. It survives the wildfires that occur every one or two decades in the fynbos where it occurs by regrowing from an underground rootstock. Pollinated by beetles, it flowers from April to November. The winged seeds remain in the woody cones until they are released after a fire, and are distributed by the wind. It is possibly the most common Proteaceae species in South Africa, and can be found in the Northern Cape, Western Cape and Eastern Cape provinces. Its current conservation status is Least Concern.

<i>Leucospermum harpagonatum</i> Species of shrub

Leucospermum harpagonatum is an evergreen trailing shrublet with leathery, line-shaped, upright leaves and small heads with eight to ten cream, later carmine-colored, strongly incurved flowers assigned to the family Proteaceae. It is reminiscent of the hottentot fig without its flowers. It is called McGregor pincushion in English and flowers from late August till early November. It is critically endangered and occurs only in a very small area in the Western Cape province, South Africa.

<i>Vexatorella amoena</i> Shrub in the family Proteaceae from the Western Cape, South Africa

Vexatorella amoena, also known as the Swartruggens vexator is an evergreen shrub of up to about 1 m (3 ft) high, that is assigned to the family Proteaceae. It has entire, inverted egg-shaped, bluish grey, leathery leaves of 1½–3 cm (0.6–1.2 in) long and 5–11 mm (0.20–0.45 in) wide on a distinct stalk, and globular flower heads of about 2 cm (0.8 in) across with pale pink flowers with extended, thick-tipped styles at the tip of the branches. The plants are flowering from September to November. It is an endemic species that is restricted to the Western Cape province of South Africa.

<i>Vexatorella obtusata</i> Species of shrub in the family Proteaceae from the Western Cape, South Africa

Vexatorella obtusata is an evergreen shrub, with narrow, leathery leaves and about 2 cm big, globular flowerheads consisting of well scented, creamy pink flowers, from which a long style with a thickened tip extends. Two subspecies are distinguished, both restricted to different parts of the Western Cape province of South Africa. The creeping V. obtusata subsp. obtusata, also known as the Montagu vexator flowers from September to December, and the upright V. obtusata subsp. albomontana, also known as the Witteberg vexator, that has flowers between August and November.

<i>Vexatorella latebrosa</i> Shrub in the family Proteaceae from the Western Cape, South Africa

Vexatorella latebrosa, also known as the Robertson vexator, is an evergreen, upright shrub of up to about 1½ m high, from the family Proteaceae. It has entire, long inverted egg-shaped, bluish grey, leathery leaves that are line-shaped to very narrowly spade-shaped in outline, 5–6½ cm (2.0–2.6 in) long and 2–3 mm (0.08–0.12 in), and mostly solitary globular flower heads at the end of the branches of 2½–3 cm (0.8 in) across with scented, pink to carmine flowers with extended, styles with a thickened tip. The plants are flowering from August to September. It is an endemic species that is restricted to the Western Cape province of South Africa.

References

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  2. "Definition of Ebractate". www.greengonzo.com. Archived from the original on 2017-04-28. Retrieved 2017-04-27.
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  5. Ralph Simon; Marc W. Holderied; Corinna U. Koch; Otto von Helversen (2011). "Floral acoustics: Conspicuous echoes of a dish-shaped leaf attract bat pollinators". Science. 333 (6042): 631–633. Bibcode:2011Sci...333..631S. doi:10.1126/science.1204210. PMID   21798950. S2CID   5035286.
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  10. Alex Casha Flora of the Maltese Islands , p. 287, at Google Books