Page 38 - Volume 2, Issue 1, January 2009

© Benaki Phytopathological Institute
New weed records from Greece 39
species at low densities in cotton crops. The
plant seemed to grow normally in the area,
reaching maturity and producing seeds. Ob-
servations and information received in sub-
sequent years from the above two areas in-
dicated the continuing occurrence of the
species at low densities with no evidence
for a fast spreading up to present.
S. spinosa, a native to tropical countries
of South America, has become a common
weed particularly in cotton and soybean
fields in the USA, Mexico, Argentina, Chile,
Peru and Uruguay, as well as in Australia (4).
In Europe it has been reported only from Ro-
mania (8). It is regarded as an invasive weed
presenting a risk mainly for the Mediterra-
nean region (4).
It is an annual species reproducing by
seeds (9). The plant reaches a height of
about 1 m, with an upright stem, woody
at the base, much branched and covered
with hairs. The leaves are alternate, elon-
gated, 2-4 cm long, with toothed margins.
At the base of the petiole there are two fil-
iform stipules shorter than the petiole (Fig-
ure 4). Flowers are axillary, single or in small
clusters at the end of short pedicels, with
5 white to light yellow petals. The fruit is a
capsule consisting of a ring of 5 mericarps,
each with two sharp spines at the tip (Figure
5). The ring breaks up at maturity releasing
one seed per mericarp. The number and the
shape of the mericarps are the safest charac-
teristics that distinguish C. spinosa (3) from
C. rombifolia (12) and possibly other species.
Based on the above information it seems
most likely that G. ciliata has been intro-
duced to Greece since some time ago and
is already established in the country while
S. spinosa has recently entered the coun-
try and is now spreading and acclimatized.
Results of a field survey through other im-
portant agricultural areas of the country are
needed before a sound conclusion on the
distribution and importance of the two spe-
cies can be drawn.
Other important weed species additions
to the Greek flora during the last years and
the need for measures to effectively prevent
their spread have been reviewed in a previ-
ous article (1).
Literature Cited
Anagnou-Veroniki M., Papaioannou-Souliotis P., 1.
Karanastasi E. and Giannopolitis C.N. 2008. New
records of plant pests and weeds in Greece,
1990-2007. Hellenic Plant Protection Journal 1:
55-78.
DAISIE, European Invasive Alien Species Gate- 2.
Figure 5. Fruit of S. spinosa at various stages of maturity (top)
and the 2-spined mericarps (bottom). Each fruit is breaking up
into 5 mericarps.
Figure 4. A shoot of S. spinosa bearing leaves, the short
stipules (arrow) at the base of the petioles and flower buds.
Details of the flower are shown in 4a.
4a