Capsule (fruit)

In botany a capsule is a type of simple, dry, though rarely fleshy dehiscent fruit produced by many species of angiosperms (flowering plants).[1][2]

Pyxidium (PSF)
Pyxidium

Origins and structure

The capsule (Latin: capsula, small box) is derived from a compound (multicarpeled) ovary.[2] A capsule is a structure composed of two or more carpels. In (flowering plants), the term locule (or cell) is used to refer to a chamber within the fruit. Depending on the number of locules in the ovary, fruit can be classified as uni-locular (unilocular), bi-locular, tri-locular or multi-locular. The number of locules present in a gynoecium may be equal to or less than the number of carpels. The locules contain the ovules or seeds and are separated by septa.

Dehiscence

In most cases the capsule is dehiscent, i.e. at maturity, it splits apart (dehisces) to release the seeds within. A few capsules are indehiscent, for example those of Adansonia digitata, Alphitonia, and Merciera. Capsules are often classified into four types, depending on the type and location of dehiscence (see Simpson Fig 9.41[2] and Hickey & King [3]).

Lilium candidum MHNT.BOT.2011.18.27
Lilium candidum dehiscing

Loculicidal capsules possess longitudinal lines of dehiscence radially aligned with the locules, i.e. not at the septa, along the midrib or dorsal suture (seam) of the locules. If septa are absent, the dehiscence lines lie between the placentae. This type is common among many members of the Liliaceae such as Lilium (see illustrstion).

Septicidal capsules have dehiscence lines aligned with the sutures of the ovary septa or placentae, that is between the carpels.

Both loculocidal and septicidal capsules split into distinguishable segments called valves. The valves are a part of the pericarp (fruit wall) that has split away, without enclosing the seed or seeds. The borders of the valves may or may not coincide with the borders of carpels. These valves may remain attached to the fruit or fall off. In septicidal capsules the valves remain in place. In some capsules, the split occurs between carpels, and in others each carpel splits open.

Circumscissile capsules (pyxide, pyxis, pyxidium or lid capsule) have a transverse, rather than longitudinal, dehiscence line, so that the upper part of the capsule dehisces, usually forming a terminal lid (operculum) that opens (see illustration). An example is Plantago. A variant is the Septifragal capsule (valvular capsule) in which the outer walls break away from the septa and (usually axile) placentae as valves.

Poricidal capsules dehisce through pores (openings) in the capsule, as in Papaver, the seeds escaping through these pores.

Spathoglottis flwrs
Flowers and developing fruit capsules of the ground orchid Spathoglottis plicata

Examples of other plants that produce capsules include nigella, orchid, willow, cotton, and jimson weed.[2][4]

Specialised capsules

Milkweed-in-seed
Dehiscence of the follicular capsule of Asclepias syriaca

Some dry dehiscent fruits form specialised capsule-like structures. A follicle is derived from a single carpel that splits along a suture, as in Magnolia, while a legume splits along two sutures, and are a defining feature of the Fabaceae. Some variants of legumes that have retained vestigial sutures include loments that split transversly into segments, each with a single seed, and indehiscent legumes, such as Arachis hypogaea (peanuts). Capsules derived from two carpels include silicles and siliques that dehisce along two suture lines but retain a partition called the replum, which is a septum with attached seeds. While both are characteristic of Brassicaceae, silicles is at least as broad as it is long, and vice a versa. A schizocarp is derived from a compound ovary with two or more locules which then separate radially as one of the above types, such as a schizocarp of follicles, as in Asclepias (Asclepiadoideae) (see illustration).

A mericarp is a portion of the fruit that separates from the ovary to form a distinct locule unit which encloses the seed, usually-nut-like, as in Apiaceae in which the mericarps are joined by a stalk (carpophore). Thus a schizocarp of mericarps is a structure in which the carpels of a single ovary split to form mericarps. A schizocarp of nutlets is derived from a carpel that becomes lobed, and the lobes become nutlets that split apart. Examples include Boraginaceae and most Lamiaceae, where the styles are attached between the ovary lobes.[2][4]

Nuts

Capsules are sometimes mislabeled as nuts, as in the example of the Brazil nut or the Horse-chestnut. A capsule is not a nut because it releases its seeds and it splits apart. Nuts, on the other hand, do not release seeds as they are a compound ovary containing both a single seed and the fruit. Nuts also do not split. In the Brazil nut, a lid on the capsule opens, but is too small to release the dozen or so seeds (the actual "Brazil nut" of commerce) within. These germinate inside the capsule after it falls to the ground.

See also

References

  1. ^ Chisholm, Hugh, ed. (1911). "Capsule" . Encyclopædia Britannica (11th ed.). Cambridge University Press.
  2. ^ a b c d e Simpson 2011, Simple fruit types pp.384–386
  3. ^ Hickey & King 2000, Capsule dehiscence p. 136
  4. ^ a b Dahlgren, Clifford & Yeo 1985, Fruit p. 15.

Bibliography

Antirrhineae

The Antirrhineae are one of the 12 tribes of the Plantaginaceae family. It contains the toadflax relatives, such as snapdragons. They are probably most closely related to the turtlehead tribe (Cheloneae) and/or a large and badly resolved core group of their family including plants as diverse as water-starworts (Callitriche), foxgloves (Digitalis), and speedwell (Veronica). The Antirrhineae include about 30 genera with roughly 320 species, of which 150 are in genus Linaria. The type genus is Antirrhinum L.

Ayenia compacta

Ayenia compacta is a species of shrub in the mallow family known by the common name California ayenia.

It is native to California, Arizona, and Baja California, in the Sonoran Desert and its Colorado Desert, and in the sky islands of the Mojave Desert.

Calochortus clavatus

Calochortus clavatus is a species of mariposa lily known by the common name clubhair mariposa lily.

It is endemic to California where it is found in forests and on chaparral slopes.

Calochortus striatus

Calochortus striatus, known by the common name alkali mariposa lily, is a species of mariposa lily native to California and into Nevada.It is a vulnerable species on the California Native Plant Society Inventory of Rare and Endangered Plants.

Claytonia virginica

Claytonia virginica, the Virginia springbeauty, eastern spring beauty, grass-flower or fairy spud, is an herbaceous perennial in the family Montiaceae. Its native range is eastern North America. Its scientific name honors Colonial Virginia botanist John Clayton (1694–1773).

Corsia

Corsia is a little-studied plant genus from the monocotyledon family Corsiaceae. It was first described in 1877 by Italian naturalist Odoardo Beccari and contains 25 species, all of which lack chlorophyll and parasitize fungi for nutrition. All 25 species are distributed through New Guinea, the Bismarck Archipelago, the Solomon Islands and Queensland, Australia.

Elattostachys xylocarpa

Elattostachys xylocarpa, known as the white tamarind or short-leaf beetroot is a common rainforest tree of eastern Australia. Found in the drier rainforests, which are based on volcanic soils. From as far south as the Orara River in northern New South Wales to Bowen in tropical Queensland. The name Elattostachys refers to "little spikes", a flower feature of other plants in this genus. xylocarpa refers to the hard woody fruit.

Euphorbia albomarginata

Euphorbia albomarginata (formerly Chamaesyce albomarginata), whitemargin sandmat or rattlesnake weed, is a small low-growing annual, in the spurge family (Euphorbia, Euphorbiaceae) native to desert, chaparral, and grassland habitats of southwestern North America, from southern and central California to Northern Mexico and Louisiana.

It can be easily identified by its small size, dusty green leaves, very flattened growth pattern, and the white circular margin around the edge of its burgundy centered flowers. It is the only member of the former Chamaesyce genus that is native to the Santa Monica Mountains, although four invasive species have been introduced there, and lack a white margin on the flower. As with other typical members of the Euphorbia family, it has a white milky sap, and is poisonous. It is one of only 11 members of the Euphorbia native to California, and one of four native to the Santa Monica Mountains.

Euphorbia ingens

Euphorbia ingens is a species of plant in the genus Euphorbia and the family Euphorbiaceae. It is native to dry areas of southern Africa. It is popularly known as the "candelabra tree", and its milky latex can be extremely poisonous, and a dangerous irritant.

Fruit

In botany, a fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after flowering.

Fruits are the means by which angiosperms disseminate seeds. Edible fruits, in particular, have propagated with the movements of humans and animals in a symbiotic relationship as a means for seed dispersal and nutrition; in fact, humans and many animals have become dependent on fruits as a source of food. Accordingly, fruits account for a substantial fraction of the world's agricultural output, and some (such as the apple and the pomegranate) have acquired extensive cultural and symbolic meanings.

In common language usage, "fruit" normally means the fleshy seed-associated structures of a plant that are sweet or sour, and edible in the raw state, such as apples, bananas, grapes, lemons, oranges, and strawberries. On the other hand, in botanical usage, "fruit" includes many structures that are not commonly called "fruits", such as bean pods, corn kernels, tomatoes, and wheat grains. The section of a fungus that produces spores is also called a fruiting body.

Galanthus

Galanthus (snowdrop; Greek gála "milk", ánthos "flower") is a small genus of approximately 20 species of bulbous perennial herbaceous plants in the family Amaryllidaceae. The plants have two linear leaves and a single small white drooping bell shaped flower with six petal-like (petaloid) tepals in two circles (whorls). The smaller inner petals have green markings.

Snowdrops have been known since the earliest times under various names, but were named Galanthus in 1753. As the number of recognised species increased, various attempts were made to divide the species into subgroups, usually on the basis of the pattern of the emerging leaves (vernation). In the era of molecular phylogenetics this characteristic has been shown to be unreliable and now seven moleculary-defined clades are recognised corresponding to the biogeographical distribution of species. New species continue to be discovered.

Most species flower in winter, before the vernal equinox (20 or 21 March in the Northern Hemisphere), but some flower in early spring and late autumn. Sometimes snowdrops are confused with the two related genera within the tribe Galantheae, snowflakes Leucojum and Acis.

Glaucium corniculatum

Glaucium corniculatum, the blackspot hornpoppy or red horned-poppy, is a species of the genus Glaucium in the poppy family (Papaveraceae). It is an annual flowering plant, occurring in southern Europe, and grows up to 1 foot (30 cm) high. The stem and leaves are hairy, the capsule fruit is covered with stiff hair, the flower is red, with a black spot on the base of the tepal bract, which has a yellow margin around it. The flower appears from June until August.

Mazus radicans

Mazus radicans, commonly known as swamp musk, is a wetland herb in the family Phrymaceae, native to the South Island of New Zealand.

Taxonomy of Liliaceae

The taxonomy of Liliaceae has had a complex history since the first description of this flowering plant family in the mid-eighteenth century. Originally, the Liliaceae or Lily family were defined as having a "calix" (perianth) of six equal-coloured parts, six stamens, a single style, and a superior, three-chambered (trilocular) ovary turning into a capsule fruit at maturity. The taxonomic circumscription of the family Liliaceae progressively expanded until it became the largest plant family and also extremely diverse, being somewhat arbitrarily defined as all species of plants with six tepals and a superior ovary. It eventually came to encompass about 300 genera and 4,500 species, and was thus a "catch-all" and hence paraphyletic taxon. Only since the more modern taxonomic systems developed by the Angiosperm Phylogeny Group (APG) and based on phylogenetic principles, has it been possible to identify the many separate taxonomic groupings within the original family and redistribute them, leaving a relatively small core as the modern family Liliaceae, with fifteen genera and 600 species.

The Liliaceae emerged from the Liliales order, separating from its sister clade around 52 million years ago (mya), and diversifying around 34 mya. Of the major clades, the Lilieae arose in Eurasia while the Medeoleae arose in North America but was subsequently dispersed, as may have the Streptopoideae and Calochortoideae. Liliaceae fossils have been dated to the Paleogene and Cretaceous eras in the Antarctic.

The Liliaceae probably arose as shade plants, with subsequent evolution to open areas including deciduous forest in the more open autumnal period. This was accompanied by a shift from rhizomes to bulbs, to more showy flowers, the production of capsular fruit and narrower parallel-veined leaves.

While the suprageneric (above genus level) structure of the family has varied greatly with its ever-changing circumscription, as currently constituted the family consists of three subfamilies, Lilioideae, Calochortoideae and Streptopoideae. Lilioideae is further divided into two tribes, Medeoleae and Lilieae. The three subfamilies contain fifteen genera and approximately 600 species in all.

Tolmiea menziesii

The plant Tolmiea menziesii () is a member of the genus Tolmiea. It is known by the common names youth on age, pick-a-back-plant, piggyback plant, and thousand mothers.

It is a perennial plant native to the West Coast of North America, occurring in northern California, Oregon, Washington, British Columbia and southern Alaska. It occurs as a naturalised plant or garden escape in Scotland, parts of Wales, Northern Ireland and northern and western parts of England.

Triadenum fraseri

Triadenum fraseri, known by the common names of bog St. John's wort, Fraser's St. John's wort, or Fraser's marsh St. John's wort, is a perennial flowering plant in the family Clusiaceae that appears natively in New England, northeastern and north Central United States and lower Canada in wetlands habitats of "bogs, marshes, swales, sedgy meadows, moist sandy (even marly) shores, conifer swamps and alder thickets". The species common name is named after John Fraser (1750–1811), a Scottish botanist and widely travelled plant collector.

Weigela subsessilis

Weigela subsessilis, the Korean weigela, is a species of flowering plant in the honeysuckle family native in Korea. It can be found on most of the mountains of Korea, except for the norther sides because the temperatures are very low. As the species is highly resistant to shade, cold, salt and even pollution, it is also found in deep forests or near the seas.

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