Dendrobium amethystoglossum hails from the island of Luzon, in the Philippines. It is a relatively large-growing Dendrobium, though smaller growing forms are to be had. My plant grows in a clay pot, as the stems do not grow directly upwards, but apically tend to arch out, making the plant rather top-heavy. The canes are quite thick, growing to around 45 cm tall, or more, and become leafless after 1 or 2 years. The leaves, though fairly leathery, are not as thick as those of D. phalaenopsis.
The flowers are produced in dense, pendulous racemes produced at the apex of both leafed and leafless canes. This tends to occur following a dry and cool rest period that usually coincides with our winter, although plants can produce the odd raceme at any time of the year. I have not noticed this species to produce scent, though many sources claim it to be fragrant.
For a long time, I had difficulty flowering my plant; it just ceaselessly produced cane after cane, each being taller and thicker than the preceding one. Whereas possessing a plant that rapidly increases in size is great, such prolific vegetative growth should not be at the expense of bloom production. I now place my plant somewhere cooler as soon as growth is nearing completion, as this appears to force the plant to rest and, subsequently, to flower. Many sources list this species as being a warm to cool grower, but my experience is that if you keep it warm all year round, it will not bloom well.
Even at its best, this species does not generally produce huge amounts of flowers for me, but that may be due to a number of factors, ranging from my growing methods to the genetics of the individual plant. The individual racemes are very attractive, with small, densely packed flowers that are mainly white with lovely, amethyst-purple lips (hence the name amethystoglossum). The flowers last for about three weeks.