Flora Unveiled

Crop Domestication and Gender j 39

39 39

has broken cleanly from the brittle rachis, whereas the cultivated grain leaves a rough edge

where the spikelet has torn from the tough rachis (Figure 3.4B).

The artificial selection of a tough- rachised wheat variety probably took place under con-

ditions of horticulture during the early Neolithic period around 10,300– 10,000 years ago.^21

In other words, farmers began planting the seeds of wild cereals in gardens before they had

altered their traits to the domesticated forms by artificial selection. Different methods of

harvesting the cultivated grain would have selected for different traits. For example, the

easiest harvesting method, beating the ripe spikelets of intact plants into a basket, would

tend to select the seeds of brittle- rachised individuals and leave the tough- rachised ears

behind. However, if stalks at the nearly ripe, yellow- green stage (when the abscission zones

of the spikelets have not yet fully matured) were either harvested by sickle or by uproot-

ing, spikelets with tough- rachises that were able to survive this rough treatment might be

(b) Long springy

awns with

backward

pointing

barbs

Pointed glume

tips facing

backward like

arrow tangs

Fragile,

ineective

awns

Poorly

developed

barbs on

glumes

One segment of

the semi-tough

rachis

One segment of

the brittle rachis

A single

disarticulated

spikelet

Spikelet

Rachis

A ripe ear in the

process of shattering

A fully-ripe ear A single spikelet

from a threshed ear

WILD

DOMESTICATED

Ripe spikelets

disarticulating

Figure 3.4 Continued