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 often (but not always) 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.

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.

Bats may detect acoustic signals from dish-shaped bracts such as those of Marcgravia evenia . [3]

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.

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.

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 [4] In other words, the epicalyx is a group of bracts resembling a calyx or bracteoles forming a whorl outer to the calyx. [5] 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. [6] 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, [7] crocuses, [8] 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 spurge family (Euphorbiaceae). "Euphorbia" is sometimes used in ordinary English to collectively refer to all members of Euphorbiaceae, not just to members of the genus. Some euphorbias are commercially widely available, such as poinsettias at Christmas. Some are commonly cultivated as ornamentals, or collected and highly valued for the aesthetic appearance of their unique floral structures, such as the crown of thorns plant. Euphorbias from the deserts of Southern Africa and Madagascar have evolved physical characteristics and forms similar to cacti of North and South America, so they are often incorrectly referred to as cacti. Some are used as ornamentals in landscaping, because of beautiful or striking overall forms, and drought and heat tolerance.

Inflorescence Term used in botany to describe a cluster of flowers

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 on the axis of a plant. 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. One can also define an inflorescence as the reproductive portion of a plant that bears a cluster of flowers in a specific pattern.

<i>Hydrangea macrophylla</i> Species of flowering plant in the family Hydrangeaceae

Hydrangea macrophylla is a species of flowering plant in the family Hydrangeaceae, native to Japan. It is a deciduous shrub growing to 2 m (7 ft) tall by 2.5 m (8 ft) broad with large heads of pink or blue flowers in summer and autumn. Common names include bigleaf hydrangea, French hydrangea, lacecap hydrangea, mophead hydrangea, penny mac and hortensia. It is widely cultivated in many parts of the world in many climates. It is not to be confused with H. aspera 'Macrophylla'.

Spikelet 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.

Cyathium

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

<i>Protea neriifolia</i> Species of flowering plant in the family Proteaceae

Protea neriifolia, also known as the narrow-leaf sugarbush, oleander-leaved sugarbush, blue sugarbush, or the oleanderleaf protea, is a flowering plant in the genus Protea, which is endemic to South Africa.

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 and List of Latin and Greek words commonly used in systematic names.

Stifftioideae Subfamily of flowering plants

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

<i>Serruria elongata</i> Small shrub in the protea family from South Africa

Serruria elongata or long-stalk spiderhead is a plant belonging to the protea family. It is an erect, hairless shrublet of 1–1½ m (3½–5 ft) high with densely set, alternate, finely divided leaves lower down the plant, with needle-like segments. On top of an up to 30 cm (12 in) long inflorescence stalk are several, loosely arranged heads of pin-like, densely silvery-haired flower buds, each of which opens with four curled, magenta pink corolla lobes. The species is endemic to the southern Western Cape province of South Africa. It flowers during the southern hemisphere winter and early spring, between June and September.

<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 bolusii</i> Shrub in the family Proteaceae from the Western Cape of South Africa

Leucospermum bolusii is a shrub native to South Africa. It grows to 1.5 m in height, and has nearly hairless leaves with a single apical tooth. The leaves are oval shaped and range from 25–45 mm (0.98–1.77 in) in length. The flower heads are about 2 cm in diameter, slightly flattened globe shaped, are set on a stalk of about 1 cm and crowded with up to eight together at the tip of the branches. They each contain 50–100 small, sweetly scented creamy white flowers, that later turn light pink. Flowering takes place between September and December. It is called Gordon's Bay pincushion in English and witluisiesbos in Afrikaans.

<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 alpina</i> Shrub in the family Proteaceae from Namaqualand, South Africa

Vexatorella alpina, the Kamiesberg vexator, is an evergreen, upright shrub of up to about 1½ m high, in the family Proteaceae. It has entire, long inverted egg-shaped, bluish grey, leathery leaves of 3–4½ cm (1.2–1.8 in) long and 5–13 mm (0.2–0.5 in) wide on a distinct stalk, and globular flower heads of about 2 cm (0.8 in) across at the tip of the branches, and consisting of pale pink flowers with extended, thick-tipped styles. The plants are flowering from September to November. It is an endemic species that is restricted to the Kamiesberge in 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.

<i>Mimetes hottentoticus</i> Shrub in the family Proteaceae from Western Cape province of South Africa

Mimetes hottentoticus is an evergreen, upright shrub of 1½–3 m (5–10 ft) high from the family Proteaceae. It has silvery, broadly egg-shaped to egg-shaped leaves with three small teeth crowded at the tip. The flower heads and subtending leaves form a cylindric inflorescence, topped with a tuft of smaller, more or less upright silvery or pinkish leaves. Each flowerhead contains 8–12 flowers with conspicuously red styles, that are all parallel, projected straight up, pushing against the leaf subtending the higher flowerhead. The styles end in a short white zone topped by a thick blackish pollen presenter. Flowers can usually be found from January till March, few may persist into May. It is called silver pagoda or matchstick pagoda in English and Hottentotstompie in Afrikaans.

References

  1. "the definition of bracteate". Dictionary.com. Archived from the original on 2017-04-28. Retrieved 2017-04-27.
  2. "Definition of Ebractate". www.greengonzo.com. Archived from the original on 2017-04-28. Retrieved 2017-04-27.
  3. 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.
  4. Darpan, Pratiyogita (June 2006). Competition Science Vision. Pratiyogita Darpan. p. 136.
  5. "Archived copy" (PDF). Archived from the original (PDF) on 2010-12-14. Retrieved 2010-08-15.{{cite web}}: CS1 maint: archived copy as title (link)
  6. "epicalyx – Dictionary of botany". Botanydictionary.org. Archived from the original on 2012-05-01. Retrieved 2012-04-29.
  7. Richard Lynch The Book of the Iris , p. 203, at Google Books
  8. Alex Casha Flora of the Maltese Islands , p. 287, at Google Books