So, I set up a track for 10 long and 10 short
awns (Fig. 1C) and let them race it out over
five days, wetting them and tracking their
movement and distance travelled each day
(Fig. 1E). The hot favourites to win the Blue
race were the lanky Awnsain Bolt and Awnsafa
Powell (later disqualified for imbibing
an illegal substance: coffee) while Shellyin
like we did
r (of 1876)
orris
waZulu-Natal, Pietermaritzburg, South Africa
[email protected]
in 1876). Using a bell
anipulate humidity,
e awns of European
ennata) uncoil when
hen drying, thereby
nd what physics une
also got his engirace
(KBE FRS, fifth
im a sensitive awn hyangle
of twist, which
breath: intriguingly it
e ‘dry’ end when the
ped in alcohol.
nd some Australians
ter) I decide to find
opic awns of our fand
palatable grass,
ig. 1A), work and
re better than short
eed across the soil to
a suitable germination site. The bigeniculate
(having two bends, or ‘knees’’) seed
awns of T. triandra vary from about 30 to
80 mm in length (Fig. 1B). The basal, helically
coiled section below the last knee of
the awn is the part that twists (see video:
https://youtu.be/TYC_48b5No8), moving
the awn across the ground. I expected that
long awns would be able to move faster
and further than short awns can because of
their longer ‘power unit’, thereby conferring
some ecological advantage.
E
B
racetrack for comparing awn movement, (D) the deep groove
ent track of a long and a short awn.
Grassroots Vol 20 No 2 June 2020