I noticed that not all grass stems seems to be used for reproduction. When growing freely, it seems there are two heights of grass: there's the main ground-cover (stolon or tillers, maybe?), and there's the tall stems that distribute pollen and seed (looks kind of like wheat/grain/cereal, I guess). I don't know if it's a polymorphism or if perhaps the two are simply a generation apart. My question is, what are the taller, stronger, reproductive stems called?

Like the tall grass on the right, here. It's all tall compared to the mown lawn on the left, but you can see some is taller, and in this case kind of brown/yellow.


Here's a diagram. I thought maybe culm or meristem, but they appear refer to to be fairly localized segments. https://commons.wikimedia.org/wiki/File:Grassy_grass_plant.svg

  • 1
    Looking at your diagram, I'd say culm is what you are looking for. There is a flowering culm and a (vegetative) culm lower down. That said, when I did a quick search there seemed to be some conflicting descriptions of the parts of grass. You'd think they'd have this sorted by now! I do know that meristems are the points where new cells are created and differentiated. So, whatever creates the seed parts has meristem cells.
    – Tim Nevins
    Oct 24, 2019 at 13:20
  • You've answered your own question with that diagram - the taller, flowering parts are flowering culms. Each individual plant in your lawn would produce these if left unmown - also, all cereals are actually types of grasses, so yes, the flowering parts are similar to cereal/grain crops.
    – Bamboo
    Oct 24, 2019 at 13:39
  • @TimNevins I think you might be right. When in doubt, I check the etymology, and culmus arista seems to refer to a corn stalk or the stalk of the awn.
    – voices
    Oct 24, 2019 at 15:01
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    The task of a tiller is to generate enough resources to produce a full culm with flowers and seed. The distinguishing feature of a culm is it is hollow and stiff. The tiller may generate insufficient resources to produce a tall culm plus flowers plus seed, perhaps due to late in the season. The result can be either a hollow culm with no seed head (as noted in question), or as in the case of foxtail a curiously short culm of a few inches with full head of flowers and seed. Oct 24, 2019 at 15:53


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