Schiedea attenuata is an erect, sparingly branched shrub that grows up to 75 cm tall, and in cultivation, it can form massive hanging plants with stems reaching up to 100 cm long. The stems are often swollen at the nodes and compressed-terete, featuring glabrous or very sparsely puberulent surfaces with minute, ± purplish, weakly hooked, or curved hairs. It has a fibrous root system. The leaves are simple and opposite, with linear-lanceolate or linear-elliptic, falcate blades. The blades measure 5.3–7 cm long (up to 12 cm in cultivation) and 5–7 mm wide (up to 11 mm in cultivation). They have a long-attenuate apex and a narrowly acute base that gradually tapers and is weakly connate. The lower surfaces and margins near the base are very sparsely puberulent. The blades are thick, firm, somewhat succulent, and glossy, with slightly revolute margins. Typically, one vein, the midrib, is prominently raised on the abaxial surface and impressed on the adaxial surface. The leaves are sessile and lack stipules. The flowers form in terminal inflorescences with 14 to 66 flowers (up to 70 in cultivation), measuring 4 to 9 cm long (up to 15 cm in cultivation). The inflorescence is diffuse, with branches and pedicels giving a one-sided effect. The bracts are pale green to purple adaxially, with internodes 3–28 mm long and pedicels 8–19 mm long. The flowers are bisexual (perfect). The sepals are 4–5 mm long, lanceolate, greenish-white or yellowish-white adaxially, often pale purple abaxially, with conspicuously scarious (thin, dry, and membranous) margins and a weakly acuminate apex. The corolla (petals) is absent. There are 10 stamens with dimorphic filaments and subequal yellow anthers. The ovary is superior, 1-celled, with free-central ovule placentation and 5 to 7 styles. The fruit is a broadly ovoid capsule approximately 3.3 to 4.5 mm long. The seeds are 0.5 to 0.6 mm long, orbicular-reniform, compressed, with transversely rugose faces and papillose margins. The seed coat cells have obtuse to rounded margins, with starchy perisperm (layer of nutritive tissue that surrounds the embryo of a seed), and lack true endosperm. It is native to diverse mesic forests on vertical cliffs, typically found around 790 meters.