Are all bamboo shoots edible?

Yes and No....

Bamboo shoots can contain cyanogenic glycosides, which when chewed, releases Hydrogen cyanide. The levels of this chemical determines the edibility and taste of the bamboo shoots. High levels results in an unpalatable level of toxicity - and an incredibly bitter taste. This acts as a natural defence for the bamboo, to prevent herbivores from eating the new emerging shoots. This is good when growing bamboo, but not so good  when you are wanting to eat it. The good news however is that the potentially toxic chemicals are easily broken down when boiled in water, making consumption perfectly safe. Preparation is therefore essential in all species except for some species like  the Nastus Elatus, which can be consumed raw. 

So....back to the question of whether ALL bamboo shoots are edible. In a sense, yes they are, but only with carefull preparation of the very bitter tasting ones by boiling the shoots multiple times (changing the water inbetween), to reduce the bitter taste and break down the toxins. Some bamboo species however have naturally lower levels of the cyanogenic glycosides, which makes them much less bitter, and thus easier to prepare for eating. In our catalogue of bamboo species, we have maked all the bamboo species as edible if the shoots that it produces are less bitter. 

It is generally the larger growing species which produce the edible shoots, with an extensive range of flavours to suit all palettes.