A free-blooming orchid in Dendrobium auriculatum
There are orchids that have a definite blooming season, and there are those that flower just when they seem like it. Dendrobium auriculatum is a good example of the latter and is a very free-blooming plant with disproportionately large flowers compared to the stems that carry it. The flowers are from 4 to 5 cm in width and are borne singly on very wiry stems that reach almost a meter in length but only around 3 mm in diameter. As can be seen from the photo, the flowers are mainly white, with yellowish-green suffusion and stripes at the bases of the perianth segments. Showy as the flowers are, fragrance is nevertheless found wanting on this species.
This illustrates the normal habit of the flower- downward facing. But only because it bends the stems from its weight.
Seen from the sides, the large, laterally flattened, upwardly curved mentum is apparent. A mentum is formed by the bases of the sepals and ideally contains nectar as reward for potential pollinators. I said 'ideally' because many orchids dupe insects into believing that nectar is present, and what often happens is that the flowers get pollinated, but the poor insect gets nothing in return.
My plant is cultivated in lowland conditions and potted with a free-draining yet moisture-retentive mix. This species likes lots of light, and so is positioned very close to the netting above, where it also gets frequent breezes. In the wild, the species is said to inhabit elevations to 900 meters above sea level, but I have a supposition that these plants can be found at much lower altitudes.
The species name was derived from the auriculate leaf bases. In botany, an auriculate leaf is one that have their lateral bases expanded or elongated so as to give the impression that the subtending stem is being clasped. The word 'auriculate' came from the Latin word auriculatum, which means 'eared'.
Dendrobium auriculatum flowers are an enigma to me. In many species of orchids, white flowers are often fragrant at night to attract moths; the glistening coloration also renders the flowers visible at night, particularly when the moon is out.
These flowers however, have no detectable scent and therefore moths cannot be suspected as possible pollinators. Whatever the pollinator is, it must be diurnally active. But ask me not what could it possibly be, as the ecology of so many orchid taxa are unknown. Particularly for the Philippines, the current trend is to discover and name new species, and yet very little effort is being done to actually know more about the orchid- its ecology and interaction with other organisms. Merely describing new species does not constitute botany as it ought to be.
Or perhaps I am just being idealistic. Either that or I am just plainly cynical.
This illustrates the normal habit of the flower- downward facing. But only because it bends the stems from its weight.
Seen from the sides, the large, laterally flattened, upwardly curved mentum is apparent. A mentum is formed by the bases of the sepals and ideally contains nectar as reward for potential pollinators. I said 'ideally' because many orchids dupe insects into believing that nectar is present, and what often happens is that the flowers get pollinated, but the poor insect gets nothing in return.
The species name was derived from the auriculate leaf bases. In botany, an auriculate leaf is one that have their lateral bases expanded or elongated so as to give the impression that the subtending stem is being clasped. The word 'auriculate' came from the Latin word auriculatum, which means 'eared'.
Dendrobium auriculatum flowers are an enigma to me. In many species of orchids, white flowers are often fragrant at night to attract moths; the glistening coloration also renders the flowers visible at night, particularly when the moon is out.
These flowers however, have no detectable scent and therefore moths cannot be suspected as possible pollinators. Whatever the pollinator is, it must be diurnally active. But ask me not what could it possibly be, as the ecology of so many orchid taxa are unknown. Particularly for the Philippines, the current trend is to discover and name new species, and yet very little effort is being done to actually know more about the orchid- its ecology and interaction with other organisms. Merely describing new species does not constitute botany as it ought to be.
Or perhaps I am just being idealistic. Either that or I am just plainly cynical.
Do you find the flowers closing during sunset, and opens again during daytime?
ReplyDeleteThank you for the detailed information on this orchid. I grow Den auriculatum here in the NE USA. I agree 100% with you that it tends to bloom whenever it likes and is never a flush of flowers, but rather one to a few flowers at a time on bare and leafed canes. I will consider myself lucky as the flowers on my plant are highly scented.
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