In addition to the flexible hairs arising from
broad bases (here on the right), the "hair bearing plant" has got short
stiff spikes (here on
the left). If hairs
or spikes are
seen on samples, one can be sure it is Trichopherophyton
since no other plant in the Rhynie chert has got any.
Obviously these structural details are meant to prevent
herbivores creeping up to the sporangia. Therefore they are not
on the lower parts of the plant, which makes it difficult to
recognise this plant if no parts with bristles are around.