| Another ecological aspect that needs clarification is the a1leged confinement
of T. dicoccoides to rocky or stony habitats. Vavilov, in particular,
has stressed this correlation. To him it represented one of the main objections
against considering T.dicoccoides a wild progenitor of the cultivated
tetraploid wheats. But actually this alleged ecological confinement is not
universal. It is observed only in localities subjected to severe overgrazing
(as most areas in Middle Eastern countries are!). Yet, where grazing is
relatively moderate, large and dense stands of T. dicoccoides can
grow also in sites where the soil cover is deep and fairly continuous. This
is particularly evident in the Eastern Galilee, where grazing practices
have undergone a drastic change since 1948 and where a spectacular come-back
of annual and perennial grass elements can be observed. The withdrawal of
T. dicoccoides to rocks and stones under severe grazing parctices
can be explained on a basis of the seed dispersal habits of this wild wheat.
T. dicoccoides is a trypanocarpous plant, i.e, specialized to insert
its arrow-shaped spikelets into the ground. The survival of wild emmer under
natural conditions is apparently largely dependant on this ability, as is
that of Hordeum spontaneum, Avena sterilis and several other
annuals of the semi-steppe formation (Zohary 1960)1). In stoneless
sites with a continuous soil cover, the burial of spikelets depends to a
large extent on the presence of drying stalks and organic residue. When
this cover is largely removed by excessive grazing, and when the bare soid
surface is further hardened by continuous trampling, there is little chance
for the arrow-like device of the spikelet to function effectively and to
insert the seed in the soil. Among rocks and stones, however, such fruit
burial is easily achieved even under severe grazing and is independant of
a lush cover of organic matter. |