# *Galium aparine*

**Bedstraw**

**Rubiaceae**

*Galium aparine* is an annual, with either a climbing, prostrate habit,
or sometimes low and erect habit. It is thought to be native to Europe,
and is found in grassy, half-shady habitats at lower elevations, from
the California Floristic Province to Alaska. *G. aparine* is also found
on the east coast of the US (Hickman, 1993). Its time of emergence is
early fall (Puntieri and Hall, 1996). After emergence, individuals
branch from the base and can break off, producing ramets; this system of
ramification allows individuals to respond favorably to stem damage
caused by low temperatures during the fall and winter (Puntieri and
Hall, 1996).

The fruits of *G. aparine* are diacoccuses disintegrating into two round
carpels with small hooks. They are strongly adapted to ectozoochory;
dispersal by ants is an additional method of fruit dispersal, even
though the fruits lack elaiosomes (Cussan et al. 1996).

*Galium aparine* has large seeds, with a weight of 9.5 g per 1000 seeds,
and could be presumed to require more energy for germination and
seedling emergence (Cussan et al., 1996). Because of its large seed
size, Cussan et al (1996) found *G. aparine* to be the least responsive
to depth of sowing and soil aggregate size of the four weed species they
surveyed. Thompson et al. (1997) found that when heated to 51°C for at
least 4 days, germination was completely inhibited. This level of heat
in the soil might be replicated by a mulch treatment, where temperatures
can reach as high as 50-60°C.

The fungicide epoxiconazole influences the growth and development of *G.
aparine*, partly due to the inhibition of gibberellin biosynthesis
(Benton and Cobb, 1995). Spraying the the field rate of 125 g ai ha^-1^,
plants were severely stunted seven days after treatment, with plant
height reduced by 43%. This result may be more important in an
agricultural context, where the goal is not complete removal of weeds
but reduction of their competitive ability against crop species. The
post-emergence herbicide amidosulfuron applied at a rate of 30 g ai
ha^-1^ was effective at preventing new growth at the seedling stage, but
less effective at older plant stages (West, 1995). These results suggest
that the most effective application time for this herbicide is soon
after most *G. aparine* seed has germinated (i.e., March-April when
plants are small and actively growing). Corn gluten meal was shown to
reduce survival and shoot length of *G. aparine* by more than 50%, and
root development by 80%, when applied at a rate of 324 g m^-2^ (Bingaman
and Christians, 1995). The herbicide fluroxypyr is more or less
effective in controlling different populations of *G. aparine*, but the
mechanism for the differences in tolerances among populations is unclear
(Hill et al., 1996).

**Literature cited:**

Benton, J. M. and A. H. Cobb. 1995. The plant growth regulator activity
of the fungicide, epoxiconazole, on *Galium aparine* L. (cleavers).
Plant Growth Regulation 17:149-155.

Bingaman, B. R., and N. E. Christians. 1995. Greenhouse screening of
corn gluten meal as a natural control product for broadleaf and grass
weeds.

Hickman, J. C. (ed.). 1993. The Jepson manual: Higher plants of
California. Berkeley: University of California Press. 1400pp.

Hill, A. L., A. D. Courtney, and B. M. R. Harvey. 1996. An assessment of
the possible reasons for differential tolerance to fluroxypyr in
selected populations of *Galium aparine*. Weed Research 36:15-20.

Puntierei, J. G. and R. L. Hall. 1996. Density-dependent mortality,
growth and size inequality in roadside populations of the annual herb
*Galium aparine* L. Ecological Research 11:121-137.

Thompson, A. J., N. E. Jones, and A. M. Blair. 1997. The effect of
temperature on viability of imbibed weed seeds. Journal of Applied
Biology 130:123-134.

West, T. M. 1995. Response of *Galium aparine*, at two growth stages, to
post-emergence treatments with the herbicide amidosulfuron. Tests of
Agrochemical and Cultivars 16:40-41.