Cleisostoma arietinum – 365 days of orchids – day 1151


How’s this for a stunning orchid? Cleisostomas are small flowered relatives of Vanda with a range of growth habits but rather similar prettly little flowers that tend to open successively along relatively long flower spikes.

This is the ‘bent’ cleisostoma referring to the curved terete leaves. It is a warm growing species from South East Asia, India and Malaysia where it grows pendulously. We have seen related species growing in Arunachal Pradesh, North East India, and in Laos, amongst a mass of orchids (Dendrobiums, Pholidotas, Erias and others) on the lower branches of semi-deciduous trees along rivers and in open forest.

We find Cleisostomas work well mounted where their attractive growth habits can be enjoyed and the plants are able to dry out well between waterings. As this is a warm growing species we hang it high in our Warm Asia section where temperatures are highest. The bright light caused the leaves to turn purple which is how we have found similar species in the wild.


Maxillaria porphyrostele- 365 days of orchids – day 1150


Maxillaria porphyrostele was one of the first orchids to arrive at the Writhlington School Orchid Project in the early 1990’s and it is still going strong although it has been divided many times. Both small plants and larger ones are now opening their sulphur yellow flowers to welcome the spring.

The species is native to cool mountain forest in the Mata Atlantica Brazil and we have seen similar species in the mild where they grow tight to the trunk and lower branches of trees in primary forests that have a wet summer and a cooler dryer winter.

We grow the species in our Cool America section in pots and baskets with free draining compost but heavy watering during the summer months when in growth. The 2cm pseudobulbs mature in the autumn and flower spikes appear from the base of the newest bulbs in early spring, each with a striking sulfur yellow flower. Looking closely into the flower reveals the purple column which gives the species its name (Porphyrostele = purple columned). The purple extends around the base of the lip too.

The flowers are long lasting if plants are kept dry when in flower.


Dendrochilum filiforme – 365 days of orchids – day 1149


One of the great things of posting our orchids every day is that we can spot changes in flowering times and identify the plants that flower several times a year. This species last flowered in September for the Bristol University Pollination day. There are many of our cooler growing species that flower both in the Autumn and the Spring and we have observed this in the wild too. We have visited the Mata Atlantica, Barazil, in April and in October and both times we found lots of Cattleya coccinea flowering.

Back to today’s orchid, this is one of our smaller Dendrochilum species and in common with most of the genus it produces a pendant spike of delicate little fragrant flowers.

The species is native to the Philippines where it grows from 660-2250m altitude. We find that our plant does best cool and damp in our Cool Americas section (yes we know the Philippines isn’t in the Americas) as it enjoys the conditions we provide for our Masdevallias.


Dendrobium amethystaglossa – 365 days of orchids – day 1148

I hope that everyone survived Storm Ciara. The school greenhouse was unscathed but some damage was done to the school roof and so staff and students are at home this morning. It is therefore a perfect time to post my most consistent and spectacular windowsill orchid.

This plant of Dendrobium amethystaglossa has been growing on my East facing kitchen window for several years and this year has seven flower sprays each with between twenty and thirty beautiful purple and white flowers. This lovely orchid is native to the Philippines where it is reported as growing on mossy limestone cliffs at an altitude of 1400m.

It grows strong vertical canes that in a mature plant can reach 1m in height (our longest are 80cm so far), the flowers are produced in pendulous sprays from older pseudobulbs and mature bulbs produce flowers over several years.

The downwards pointing flowers presenting clear of the pseudobulbs and the lack of scent suggest that the flowers are pollinated by birds.

At school we grow this species in our Warm Asia section but as shown here it does make a wonderful house plant. On its windowsill it is watered twice a week throughout the year. The natural habitat does not experience a significant dry season.

It flowers reliably in early spring, when flowers are so valued in the house, and the flowers last over a month.


Dendrobium suffusum – 365 days of orchids – day 1147


More of our Australian species are coming into flower in our Cool Asia Section and today we will feature Dendrobium suffusum which is actually a natural hybrid. This is one of the prettiest and most floriferous of our cool growing dendrobiums that also benefits from having a lovely sweet scent.

The parents are Dendrobium kingianum and Dendrobium gracilicaule and it is a medium sized plant that grows into a specimen quite quickly. Pseudobulbs up to 40cm high carry spays of many 1cm flowers with a lovely fragrance. In the past this clone ‘Writhlington’ has won two Certificates of cultural Commendation from the RHS.

At school this species grows in Cool Asia(min.10C) with good light with lots of water in the summer, but with less water in the winter.