A call for better bamboo observations (and some hints on how to do them)

On may the 6th, 2024, I reached out on the iNat forum to call for better bamboo observations.
Partakers in the conversation asked for a journal post with explicating photos, so here is a first try at this. I'll try to update this post when I'll get more pictures / infos about bamboo identification.

The call for better bamboo observations may be regarded world-wide, but since I live in Europa, I put up this project for Phyllostachys in Europa, since this genus seems to be the most planted one on the old continent and one which tends to “escape” easily from gardens or parks, don’t hesitate and join if you feel like it !

Bamboos are seemingly quite homogeneous in their general features and often observations of bamboos will show only some foliage and sometimes some eye-level section of the adult culm, which are far from sufficient to do the job.
Spring is the right time to observe and try to identify bamboos since identification is made from diagnostic features on the culm sheath (the “leaves” that grow directly on the sprouting culm, not on branches).

As said above, Phyllostachys is probably the main genus planted in Europa so this post will focus on it (with some hints at other common bamboos if I get the material and infos to do so). If you want to ID bamboos (or at least, make an observation with reasonable chances at getting an ID), here are the shots you should look for :

    Is it within genus Phyllostachys ?

  1. Is it within genus Phyllostachys ? It is if :

    • the culm sheaths fall
    • branches are by two (or mainly so) at the insertion nodes (sometimes just 1, rarely 3, but these are exceptions)
    • there is (not always but hey, that's just mother nature saying "f*** off ! you'll not put me in little boxes !") a +/- prominent groove, called a sulcus (kind of a little canal) or a sometimes just a flattened face, along the internode above the insertion point of the branches.

  2. Pseudosasa japonica don't leave it's culm sheaths which remain attached on the culm, giving the bush a stripped look. Phyllostachys bamboos do leave their culm sheaths which fall as the culm grow, leaving the culm of one color (be carefull : some Phyllostachys varieties do have some color strips but it's only a coloration thing : no attached parts on the culm)

    Flattened face below the insertion node of two branches, and little canal on an internode without branches.

    Creeping or clumpsing ?

  3. a general view of the plant is always a good idea, even if not sufficient, but keep it part of your observation.

    Are the culms growing tightly (few centimeters away from each other) or more distantly (few decimeters to meters apart) ?

  4. This question aims at taking apart leptomorph bamboos (the one with creeping rhizomas) from pachymorph bamboos (the one which grow in clumpses and should not expand that quickly). But I always find it difficult to take appart when you begin with bamboo observations and have no references in mind. Unfortunately I never came across pachymorph bamboos (or if so failed to recognize them as so).

    Sprouting culms

  5. look for the sprouting culm and take photos from the top of the culm (if visible) showing the culm sheaths at their opening point : we want to know if the blades are imbricate*, and if they are flat or wavy, if there are some auricles (apendix at the basis of the blade), if there are oral setae (long, very conspicuous hairs at the separation between sheath and blade).

  6. This are the top of the sprouting culm type of photo you want to achieve, but I'm unfortunately not experienced enough and I don't get what it means if the blades are intricate or not. At the top of the culm, blade are always erects, they will eventually incline downside as the culm grows and before the sheath fall.

    Blade are always little, triangular and erect as the culm emerges from the ground (culm < 50 cm). When the culm grows, blade can stay erect untill the sheath fall, or become horizontal or reflexed ("looking downward").
    The blades can be flat, "wavy" or "crinkled". I didn't get to see all the forms so here are some links to illustrations within the Flora of China :
    * I don't get what means the "imbricate" state of blades at apex of the culm : to me they always look imbricate at the apex, wether or not they will remain erect or become reflexed as the culm grows... Any clue on this is welcome !

    Auricles and oral setae

    Auricles are little apendix at the base of the blade. They may or may not come with oral setae on top of them. Oral setae can be present without auricle development.

    Sometimes the auricles and oral setae are quite conspicuous, sometimes not that conspicuous, so be carefull when looking for them.

    Here is a very conspicuous green auricle with big oral setae on Ph. bambusoides (= Ph. reticulata).

    Sheath color, spotted or not and hairyness

  7. look for a ready to fall* culm sheath : what is its color ? are they covered with small hairs or not ? do they have spots (yes or no, and if yes then are they homogeneous or of different sizes and shapes, are they dense or sparse). If the sheath already fell, is there a ring of hairs at the scar point ?

  8. The spotted sheath of Ph. cf. reticulata, vs the unspotted sheath of Ph. cf. nidularia.
    A ring of hairs at the scar place on a Phyllostachys culm (probably Ph. nidularia - to be confirmed).

    *some bamboos don’t lose their culm sheath : look for older culms to see if the sheaths fell or not : that’s an important thing to notice.


  9. Try to spot the ligula : the membraneous nail-formed thing at the separation point between sheath and blade, on the inward side. We will want to see if it has got hairs, their relative length, if the ligula is intact of if it is rather lacerated, it’s length (height) and length to width ratio.

  10. The width / height ratio is rather troublesome to represent out of nothing, so here is a chart with the different ratios used in the flora of China to mesure the ligula of your observed Phyllostachys against. The best thing with ratio is that you don't need to measure it in real life : you can just put a ruler above your photo on your computer screen and measure the width, then the height, and compute the ratio. Beware although : you will need to correctly flatten the sheath near the ligula while you shoot the photo so the ligula won't be all coiled up (which would distort the ratio you would measure afterward).

    Adult culms

  11. have a look at the grown up culms : do the new ones have some kind of white powder (i.e. : pruina) at the internodes ? do they have hairs on the young internode ? what is their color, do they have spots of other colors ? Are the older culms (generally 2 to 5 years old) of the same color ? How look the basal internode ? are there many little ones or only some gradually bigger ones ? are they swollen or not ? Are the node swollen ?

  12. Irregular tiny and somewhat rounded basal internodes are a diagnostic feature of Ph. aurea. Blackened out culms are diagnostic for Ph. nigra var nigra but beware : Ph. nigra var henonis has green culms !

    White powdery (pruina) young internode are of diagnostic caracter for some species : look for it. Sometimes it remains only a ring of white powder (pruina) underneath the node : at this place it last the most.

I submitted a false "observation" to post some squetches of Phyllostachys diagnostic caracters for identification purposes. Feel free to look at and use it if it's usefull to you. Illustrations there are free to use (CC0).

The Flora of China is a good source for ID-keys and illustrations, like this one for Phyllostachys :

Other ressources :

Any other ressources you would like to share are very welcome. Post a comment !

Posted on May 15, 2024 08:59 PM by botaflo botaflo


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