Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Gentianales
Family: Rubiaceae
Genus: Galium
Species: G. aparine
Binomial name: Galium aparine
Common name: Bedstraw, Cleaver, Clivers, Stickywiily,  Goosegrass, Stickyweed, Stickyleaf, Catchweed, Coachweed.

Cleavers is an annual herbaceous weed, a native to North America and Eurasia.  Cleavers is often found in its vegetative stage over winter and produces fruits in mid to late spring. It is often considered to be sticky because it clings tenaciously to socks, other clothing and to sheep. However, the foliage and fruits are actually armed with tiny hooks which help them "stick" to such surfaces.  It is a clambering weed with long weak stems that climb up over surrounding plants and structures such as fences, so the hooks also help keep the plant in place. 
It is a common weed in hedges and other low shrubby vegetation and is also a common weed in arable fields, as well as gardens. As they grow quite rampantly and thickly, they end up shading out any small plants that they overrun.  In some situations within crops, cleavers can cause lodging of the crop, which is where the weed climbs up over the top of crop plants such as wheat, then make them "top-heavy" and thus fall flat to the ground during windy weather. This can make harvesting of the crop more difficult.

The leaves are simple and borne in whorls of six to eight. Both leaves and stem have fine hairs tipped with tiny hooks, making them cling to clothes and fur much like velcro. The white to greenish flowers are 2-3 mm across, with four petals. It flowers in early spring to summer, with the flowers occurring in most of the leaf nodes. The fruits are clustered 1-3 seeds together; each seed is 4-6 mm diameter and is also covered with hooked hairs (a burr) which cling to animal fur, aiding in seed dispersal.

A bank cover with Galium aparine
Galium aparine Bedstraw Cleaver -001.JPG  

1-Galium aparine Bedstraw Cleaver .JPG

The little four-petalled white flower
1-Galium aparine Bedstraw Cleaver -001.JPG

1-Galium aparine-002.JPG

Galium aparine Bedstraw Cleaver .JPG

Galium aparin Bedstraw Cleaver.JPG

The seed heads with hooks
Galium aparin Bedstraw Cleaver-001.JPG

Photo showing the velcro-like hooks all over the plant.
Galium aparine Cleaver 2.jpg

Photograph shows the square stem with its hooked prickles on the four corners.
Galium aparine Cleavers.JPG

Closeup of Galium aparine stalk and the tiny hooks on the corners.

1-Galium aparine Bedstraw Cleaver -003.JPG 

Illustration Galium aparine0.jpg 
Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/