Pteris ensiformis, the slender brake,[2] silver lace fern, sword brake fern, or slender brake fern, is a plant species of the genus Pteris in the family Pteridaceae.

It is the most common ingredient of traditional herbal drinks in Taiwan containing different phenolic compounds : kaempferol 3-O-α-l-rhamnopyranoside-7-O-[α-d-apiofuranosyl-(1-2)-β-d-glucopyranoside], 7-O-caffeoylhydroxymaltol 3-O-β-d-glucopyranoside, hispidin 4-O-β-d-glucopyranoside, kaempferol 3-O-α-l-rhamnopyranoside-7-O-β-d-glucopyranoside, caffeic acid, 5-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid and 4,5-di-O-caffeoylquinic acid.

[4] This plant is resistant to arsenic-induced oxidative stress.

[5] Benzoyl-beta-D-glucoside, as well as pterosin sesquiterpenes can be found in P.

[6] Pteris ensiformis is cultivated as an ornamental plant for tropical and subtropical climate gardens, and as a house plant.