[3] Smilax jamesii is a rhizomatous perennial herb taking the form of a vine, climbing and branching to maximum lengths of 2 to 3 metres (6+1⁄2 to 10 ft).

The dark green leaves have blades up to 8 centimetres (3+1⁄8 in) long by 7 cm wide, triangular to pointed oval in shape.

The mature fruit is a blue berry just under a centimeter wide which turns maroon in color as it dries.

[4] It was discovered to be a new species when herbarium specimens thought to be Smilax californica were reexamined.

[6][7][8] It grows in moist areas such as lakesides and streambanks in mountain coniferous forest habitat.