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Platypodium elegans
''Platypodium elegans'' or the graceful platypodium is a large leguminous tree found in the Neotropics that forms part of the forest canopy. It was first described by Julius Rudolph Theodor Vogel in 1837 and is the type species of the genus. The tree has been known to grow up to 30 metres in height and have a trunk with a diameter up to 1 m at breast height. Its trunk has large holes in it, sometimes making it possible to see through the trunk. The holes provide a habitat for giant damselflies and other insects both when alive and once the tree has died and fallen over. It has compound leaves each of which is made up of 10–20 leaflets. Three new chemical compounds have been isolated from the leaves and they form part of the diet of several monkeys and the squirrel ''Sciurus ingrami''. In Panama it flowers from April to June, the flowers contain only four ovules, but normally only one of these reaches maturity forming a winged seed pod around 10 cm long and weighing 2 g. During the dry season around a year after the flowers are fertilised, the seeds are dispersed by the wind and the tree loses it leaves. The seeds are eaten by agoutis and by bruchid beetle larvae. The majority of seedlings are killed by damping off fungi in the first few months of growth, with seedlings that grow nearer the parent trees being more likely to die. The seedlings are relatively unable to survive in deep shade compared to other species in the same habitat. Various epiphytes are known to grow on ''P. elegans'' with the cactus ''Epiphyllum phyllanthus'' being the most abundant in Panama. Despite having holes in its trunk which should encourage debris and seeds to collect, hemiepiphytes are relatively uncommon, possibly due to the seeds being dispersed by wind, meaning that animals are not attracted to it to feed and then defecate. It has no known uses in traditional medicine and although it can be used for timber, the wood is of poor quality.
==Description==
''Platypodium elegans'' is a large forest tree, which forms part of the forest canopy. It can grow up to 30 m in height, with mature trees having an average crown diameter of 16 m and a diameter at breast height (dbh) of 75–100 cm.〔 Trees over 20 cm dbh grow at a rate of around 0.5 cm per year, as measured by how their dbh increases. Its trunk is fenestrated, having large and conspicuous holes in it, even so much so that it is possible to see through the trunk, meaning it can be mistaken for a strangler fig. The bark is soft and dark brown and contains a foul-smelling sap. It has compound leaves which grow up to 25 cm in length, each having 10–20 leaflets, which are 2.5–7.5 cm long, 1–3 cm wide, hairless on the upper side and positioned not quite opposite each other.〔〔 Three new compounds have been isolated from the leaves of ''P. elegans''; two ''seco''-lupane triterpenes (canaric acid and dihydrocanaric acid), as well as a coumarin, 6,7,8-trimethoxycoumarin. The mature leaves are relatively tough, requiring more than 100 g/mm2 to be applied to them to puncture them. It is deciduous, losing its leaves during the dry season, when its seeds are dispersed. The diameter of the conducting vessels in the roots are on average 69 μm, up to 98 μm and in the shoots 57 μm up to 87 μm. The trees (over 20 cm dbh) are relatively stiff compared to other trees on Barro Colorado Island (BCI), having a Young's modulus of 180,000 kg/cm2.〔
In Panama, it flowers from April to June. It was first reported to flower only every other year, but this is now known to be incorrect, although seed production can vary considerably from year to year. The flowers of ''P. elegans'' contain four ovules, but normally only the most distal ovule develops into a seed,〔 with other seeds being aborted before they mature. The pedicels are 8–12 mm long, the bracts around 2 mm long and the calyx around 4 mm long.〔 After being fertilised a winged fruit (a samara) develops quickly, but it takes around one year for the seed to mature. The fruit remains on the tree whilst the seeds develop and is thought to photosynthesise during this time. The samaras dry out during the dry season, before detaching from the tree and being dispersed by the wind over 2–3 months.〔 In Panama the seeds are dispersed between February and April, just under a year after the flowers formed.〔 Each samara normally only contains one seed, but sometimes they contain two instead, which affects their dispersal.〔 The samaras vary in size and shape between trees, but are generally similar on each individual tree. On average, they weigh around 2 g when dry, and are around 10 cm long〔 but can grow up to 16 cm.〔 Samaras containing two seeds are heavier, have a larger surface area and fall faster from the tree than those containing only one seed.〔 Each seed weighs around one third of a gram, making them relatively large compared to other trees in its habitat, but seeds that are the result of self-fertilisation are significantly lighter (by 0.03 g).〔 The cotyledons, of the seedlings remain underground after germination and only serve as a stored source of nutrients, they detach within 8 weeks of germination.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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