Involved in pectic arabinan modification in mucilage secretory cells. Acts also as a beta-D-xylosidase during the remodeling of xylans in vascular development. Hydrolysis of terminal non-reducing alpha-L-arabinofuranoside residues in alpha-L-arabinosides. Optimum pH is 4.9. Optimum temperature is 55 degrees Celsius. Expressed in leaves, stems, seedlings, roots, inflorescences, siliques and developing seeds. Expressed in the vasculature of the roots, leaves, flowers and silique. Expressed in tissues undergoing secondary cell wall thickening such as protoxylem, metaxylem, intrafascicular cambium and fibers. By sugar starvation. Delayed seeds germination resulting from an altered mucilage composition. No visible growth defects; probably due to partial redundancy with BXL2. Bxl1 and bxl2 double mutants have shortened siliques and curled leaf edges. Might be processed at the C-terminus. Belongs to the glycosyl hydrolase 3 family.