This iNat post was prompted by a novel field-observation of strange glowing-green "clumps" initially seen among rocks along a small creek within coastal oak woodland during overcast-to-drizzling weather. The scene appears in the photo from Joerg's post shown below (click it to enlarge):

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At first glance from a distance, these "clumps" looked like happy patches of moss or hornworts. It was only after a member of our group (Edith) looked closer that she realized one of the "moss clumps" was actually attached to the end of a senescent grass culm!

None of us in the group had ever seen such a thing, but it appeared to be a dead grass culm whose dense, withered inflorescence had retained much of its seed...and that seed was now profusely sprouting in place at the end of the dead culm. Numerous other dead grass stems from last year were seen in the vicinity with similar terminal "false moss clumps".