I've eaten several flowers of the Dendrobium orchid hybrid Johnathan's Glory, Dark Joy and the Australian species Dendrobium kingianum. I tried Dark Joy because it was the closest to a Dendrobium bigibbum I could find, which is sold in America as an edible flower/garnish (1). I understand this hybrid is only around 12% Dendrobium bigibbum (the rest being Dendrobium kingianum, tetraganum & falcurostrum whose flowers do not seem to be reported edible (or toxic)).
Both are soft and crunchy, easy to chew and swallow, both taste rather weakly like glue or gum, a bit like some craft beer, the hybrid "Dark Joy" was also slightly bitter. Would not add much positive to a meal except ornament (raw at least, became bland in flavor after boiling but seemed to become extremely soft, almost disintegrating. I did not have a very big sample to work with, will have to try this again next time they flower). Would probably not ruin a salad added raw in small amounts. If this flavor is typical of orchid flowers it might explain why they are not eaten much: they are not really bad tasting, but not generally good enough to become established in traditional food culture. Given their exceptional beauty perhaps people generally decide it makes more sense to look at them or use them for religious purposes than eat them.
I felt comfortable sampling this because there does not appear to be any specific record of any orchid flowers being toxic, though only a tiny percentage of the thousands of species are reported to be eaten by humans. There are a few claims on the net that all orchid flowers can be eaten safely, but it is likely not all species and varieties have been sampled.
Lawler's report on orchid toxicity suggests a very small percentage of the vast number of orchids that exist are toxic to humans. He lists only eye irritation from seed of one Cymbidium, contact dermatitis from various Cypripedium and reports of Disa chrysostachya and a Eulophia supposedly being used deliberately as human poisons in Africa. However several Cypripedium, an Epipdendrum an Oncidium and one Spathoglottis species might be narcotic (there are also reports of pollinating insects becoming intoxicated by exudation of flowers but I wondered if this is simply because of fermentation). Cypripedium spectabile, Orchis latifolia and laxiflora are avoided by cattle while Bletia verecunda, hyacinthina, Calathe discolor, Dipodium puntatum, Eulophia virens, Microtis parviflora and Thecostele poilanei are either toxic or suspected of being toxic to animals (2).
I feel very confident exploring flavors of common orchid genus like Dendrobium that lack any toxicity reports and are often used medicinally (as tonics for instance), and will be doing more of it (without eating large quantities, which is unlikely anyway give the taste so far). The beautiful and alluring Paphilopedilum is one genus I will be much more careful with as it has (apparently only very recently) been reported to include some serious toxicity used locally as an animal poison (3), this refers to the whole plant, possibly including the flowers.
The main question for me with apparently non-toxic genus like Dendrobium is whether they are soft enough to eat, several I've tried are not. I emphasize I am not in a position to recommend anyone else experiment like this. I am not an orchid or toxicology expert, rather an experienced unusual edibles enthusiast/addict (who has had the odd culinary mishap in the past, such as tingling, prickly and numb sensations in the mouth from chewing but not swallowing).
References.
1. Edible Medicinal and Non-medicinal Plants. Volume 8, Flowers. T.K. Lim. 2014.
2. Ethnobotany of the Orchidaceae L J Lawler . Orchid Biology. Reviews and Perspectives, III Edited by J Arditti. 1984.
3. Medicinal Orchids of Asia. Eng-Soon Teoh. 2016.
