Drupe

Diagram of a typical drupe (peach), showing bothfruitandseed

The development sequence of a typical drupe, a smooth-skinned (nectarine) type of peach (Prunus persica) over a7+1⁄2-month period, from bud formation in early winter to fruit ripening in midsummer

Inbotany,adrupe(orstone fruit) is anindehiscenttype offruitin which an outer fleshy part (exocarp,or skin, andmesocarp,or flesh) surrounds a single shell (thepip(UK),pit(US),stone,orpyrena) of hardenedendocarpwith aseed(kernel) inside.These fruits usually develop from a singlecarpel,and mostly from flowers withsuperior ovaries(polypyrenous drupesare exceptions).

The definitive characteristic of a drupe is that the hard,lignifiedstone is derived from theovarywall of theflower.In anaggregate fruit,which is composed of small, individual drupes (such as araspberry), each individual is termed adrupelet,and may together form an aggregate fruit. Such fruits are often termedberries,although botanists use adifferent definition ofberry.Other fleshy fruits may have a stony enclosure that comes from the seed coat surrounding the seed, but such fruits are not drupes.

Flowering plantsthat produce drupes includecoffee,jujube,mango,olive,most palms (includingaçaí,date,sabalandoil palms),pistachio,white sapote,cashew,and all members of the genusPrunus,including thealmond,apricot,cherry,damson,peach,nectarine,andplum.

The termdrupaceousis applied to a fruit having the structure and texture of a drupe,but which does not precisely fit the definition of a drupe.

Terminology

The boundary between a drupe and a berry is not always clear. Thus, some sources describe the fruit of species from the genusPersea,which includes theavocado,as a drupe,others describe avocado fruit as a berry.One definition ofberryrequires the endocarp to be less than2 mm (3⁄32in) thick, other fruits with a stony endocarp being drupes.In marginal cases, terms such asdrupaceousordrupe-likemay be used.

The termstone fruit(alsostonefruit) can be a synonym for drupe or, more typically, it can mean just the fruit of the genusPrunus.

Freestonerefers to a drupe having a stone which can be removed from the flesh with ease. The flesh is not attached to the stone and does not need to be cut to free the stone. Freestone varieties of fruits are preferred for uses that require careful removal of the stone, especially if removal will be done by hand. Freestone plums are preferred for making homegrownprunes,and freestonesour cherriesare preferred for making pies andcherry soup.

Clingstonerefers to a drupe having a stone which cannot be easily removed from the flesh. The flesh is attached strongly to the stone and must be cut to free the stone. Clingstone varieties of fruits in the genusPrunusare preferred as table fruit and for jams, because the flesh of clingstone fruits tends to be more tender and juicy throughout.

Trymais a specialized term for suchnut-like drupes that are difficult to categorize. Hickory nuts (Carya) andwalnuts(Juglans) in theJuglandaceaefamily grow within an outer husk; these fruits are technically drupes or drupaceous nuts, thus are not true botanicalnuts.

Ecology

Many drupes, with their sweet, fleshy outer layer, attract the attention of animals as afood,and the plant population benefits from the resultingdispersal of its seeds.Theendocarp(pit or stone) is sometimes dropped after the fleshy part is eaten, but is often swallowed, passing through thedigestive tract,and returned to the soil infeceswith the seed inside unharmed. This passage through the digestive tract can reduce the thickness of the endocarp, thus can aid in germination rates. The process is known asscarification.

Examples

Typical drupes includeapricots,olives,loquat,peaches,plums,cherries,mangoes,pecans,andamlas(Indian gooseberries). Other examples include sloe (Prunus spinosa) and ivy (Hedera helix).

Thecoconutis also a drupe, but themesocarpis fibrous or dry (termed ahusk), so this type of fruit is classified as a simple dry, fibrous drupe. Unlike other drupes, the coconut seed is so large that it is unlikely to be dispersed by being swallowed byfauna,but it can float extremely long distances—across oceans.

Bramblefruits such as theblackberryand theraspberryare aggregates of drupelets. The fruit of blackberries and raspberries comes from a single flower whosepistilis made up of a number of free carpels. However,mulberries,which closely resemble blackberries, are not aggregate fruit, but aremultiple fruits,actually derived from bunches ofcatkins,each drupelet thus belonging to a different flower.

Certain drupes occur in large clusters, as in the case of palm species, where a large array of drupes is found in a cluster. Examples of such large drupe clusters includedates,Jubaea chilensisin central Chile andWashingtonia filiferain theSonoran Desertof North America.

Drupe-like "fruits" are also known in manygymnospermslikecycads,ginkgosand somecypresses.

Gallery

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  Assorted drupes
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  Thepeachis a typical drupe (stone fruit)
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  'Elena', a freestoneprune plum
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  The pit of anectarine
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  Unripe drupes ofblack pepper
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  'Black Butte' blackberry, a bramble fruit of aggregated drupelets
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  A ripeareca nut
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  Ginkgo"fruits", often noted as drupe-like

See also

• Pome(polypyrenous drupe)

External links

• Identification of Major Fruit Types(archived)
• Fruits Called Nuts(archived)
• "Drupe".New International Encyclopedia.1905.