Probable beta-1,4-glucan synthase rather involved in the synthesis of the xyloglucan backbone than cellulose. Seems to work simultaneously with xyloglucan 6-xylosyltransferase. Xyloglucan is a noncellulosic polysaccharides of plant cell wall and consists of a glucan backbone substituted by xylose, galactose and fucose. Homodimer. Mainly expressed in roots, flowers and seeds, and, at very low levels, in seedlings, leaves and stems. Normal xyloglucan (XyG) levels (PubMed:32737163). Plants missing several xyloglucan synthases (e.g. CSLC4, CSLC5, CSLC6, CSLC8 and CSLC12) have no detectable XyG levels and several associated phenotypes including reduced stems height and leaves area, as well as shorter root hairs and reduced pollen tube formation ability (PubMed:32737163). Belongs to the glycosyltransferase 2 family. Plant cellulose synthase-like C subfamily.