Preparing orchids for this weeks RHS Orchid Show at Wisley is moving on a pace. Some of our plants will be on show for the first time but this plant has been a regular at spring shows more than twenty years. This wonderful orchid is one of our veteran plants and possibly our largest of member of the Pleurothallidinae (the subtribe of more than 4000 species including our Masdevallia, Stelis, Pleurothallis and Restrepia species).

The species is native to Colombia, Ecuador, Bolivia, Venezuela and Guyana at altitudes of 1300 to 3500 meters and I have seen it described as a miniature and although the flowers are small grows into a very large plant over time. Our large plant again has over a hundred flower spikes constantly flowering and a froth of flowers surrounding the plant which grows in a basket. Each flower spike lasts three years and slowly gets longer and longer. The flowers themselves are well worth a close inspection – we particularly like the ‘fangs at the tip of the synsepal (fused lateral sepals) that happens to be at the top of these non-resupinate (upside down) flowers.

We have had the species since 1999 when it was donated by a grower in Devon and it has been in flower every day since – 23 years without a break in flowering is not bad. This plant won an RHS Cultural Certificate at the London Show in 2016 and is always a thing of beauty.

It enjoys being watered well and doesn’t seem to enjoy hot summers which usually result in a bit of leaf drop. It looks its best in the spring with this winters fresh green growth and a fresh crop of flower spikes just starting to flower. We grow the plant in a hanging mushroom crate that allows it to spread.

We have two distinct varieties of this lovely African species flowering this week in the school greenhouse.

As you can see one variety, Bulbophyllum falcatum var velutinum, (above) has a much shorter and wider rachis that carries the flowers, is much greener especially in the rachis and has larger growing bulbs and leaves. The type variety (below) we call Bulbophyllum falcatum ‘red’ as it has a lot more red pigment (often on the rachis though it varies with light levels) much darker leaves and a very long, thinner, rachis that carries the flowers.

Both varieties of the species are found in tropical west and central africa from Sierra Leone to Rwanda. The species grows as an epiphyte in wet evergreen lowland forest similar to that we have explored in Rwanda.

We find this a really rewarding and easy species to grow that flowers from a young age but multiplies quickly. It likes the warmth of Warm Asia and soon drops leaves if grown too cool. We find it grows well in a basket or a pot but in a pot it may quickly grow out of its own pot and try rooting in any others near it – a littler troublesome but worth putting up with 🙂

We find Prosthechea species very rewarding orchids – free flowering, long lasting flowers and great perfumes. Most Prosthechea species, including P.venezeulana, are butterfly or moth pollinated which explains the great fragrance.

Prosthechea venxuelana will be in flower all summer. The species is native to Venezuela (as the name would suggest) as well as Colombia and Ecuador. It is reported to grow in wet lowlnd forests and so we are growing it in Warm Americas (Min 16C) at bench level where it will stay damper than plant hung high in the roof.

The flowers are large for the size of the plant and produced in profusion and as usual for the genus are beautifully scented. The plant is a little spreading in its growth habit and so we have the plant in a basket to allow it to develop into a relaxed specimen.

We have a himalayan Phalaenopsis species for you today. This is the variety of Phalaenopsis mannii with no red pigment, so similar to the ‘alba’ varieties of many species that don’t have a yellow flower ground colour.

We also have the normal variety of Phalaenopsis mannii in flower (below) and it is really interesting to compare the two.

We have seen Phalaenopsis mannii in lowland forest on several of our trips to the Himalayas, seeing it in Kalimpong, Sikkim and Assam, but we have never come across a ‘flava’ in the wild. It is always a treat to explore the natural variation of orchid species when you come across wild populations, and orchids are wonderfully variable.

The photo I took of the species in Assam clearly shows the natural habitat for the plant. The forest is seasonally dry forest and there is not sufficient rainfall or humidity for moss to grow on the branches colonised by the orchid. This plant is in the lowest branches of a large evergreen tree where light levels are quite low and it is protected from extreme desiccation in the dry season. The photograph also shows the very extensive root system this massive plant has developed over time (it must be at least twenty years old) and this will store a lot of water during dry periods as well as collecting a lot of water when it does rain.

March wouldn’t be March without Dendrobium fimbriatum flowering both in our Warm Asia section and in the foothills of the Himalayas.

Dendrobium fimbriatum is an orchid we have seen growing abundantly in Sikkim and Arunachal Pradesh in semi-deciduous trees in warm lowland forests up to about 1000m. In the wild it makes large dramatic specimens.

The photos above show it flowering a tree next to the main road to Gangtok not far from the River Teesta at about 400m above sea level (It is in the centre of the photo half way up the middle tree). The habitat here is semi evergreen forest with a distinct dry season.

Flowers are produced in small sprays of about ten flowers from along the leafless pseudobulbs from two to five years old (so don’t cut off old bulbs until they are completely dead). Its native habitat is warm and wet in the summer but distinctly dryer in the winter with a significant drop in temperature from the summer and so we find the species responds well to moving to our Cool Asia section (minimum 10C) for a few weeks in January before moving back to its normal spot in Warm Asia (minimum 17C) where it then flowers.

In Sikkim we have noticed that large plants collect a lot of dead leaves in their crowns which presumably provide additional nutrient to plants and we find that the species responds well to lots of feed and water in the summer and quickly grows long pseudobulbs. The thin leaves of the species are attractive to red spider mite and scale insects so keep an eye out for pests.