Clematicissus angustissima is a vine in the Vitaceae family, endemic to the Geraldton area of Western Australia.

[2][3] The species was first described as Vitis angustissima in 1859 by Ferdinand von Mueller, from a specimen collected by Oldfield on the Murchison River.

[4][5] In 1887 Jules Planchon reassigned it to his newly described genus, Clematicissus,[4][6] with Clematicussus angustissima being the type species.

[6] C. angustissima is a deciduous vine growing from numerous tubers.

The tendrils are leaf-opposed and the five-palmate (3-7) leaves can be entire or deeply indented.