Iris tenuis by Sereno Watson

TENUIS. Watson, Proc. Amer. Acad., xvii, 380. Rootstock elongated, very slender (a line thick); leaves thin, ensiform, about equaling the stems, four to eight lines broad; stems scarcely a foot high, 2 or 3-flowered, with two or three bract-like leaves two or three inches long; lateral peduncles very slender, as long as the bracts; spathes scarious, an inch long; pedicels solitary, very short; flowers small, white marked with yellow and purple; tube two or three lines long; segments oblong-spatulate, the sepals spreading, one and one-half inches long, the petals shorter and emarginate; anthers as long as the filaments; styles with narrow entire crests; capsule oblong-ovate, obtuse, nine lines long.]

Fig. 3.--Iris tenuis.

Fig. 3.—Iris tenuis.


THIS pretty delicate species of Iris, Fig. 3, is a native of the Cascade Mountains of Northern Oregon. Its long branching rootstocks are scarcely more than a line in thickness, sending up sterile leafy shoots and slender stems about a foot high. The leaves are thin and pale green, rather taller than the stems, sword-shaped and half an inch broad or more. The leaves of the stem are bract-like and distant, the upper one or two subtending slender peduncles. The spathes are short, very thin and scarious, and enclose the bases of their rather small solitary flowers, which are “white, lightly striped and blotched with yellow and purple.” The sepals and petals are oblong-spatulate, from a short tube, the sepals spreading, the shorter petals erect and notched.

The peculiar habitat of this species doubtless accounts in good measure for its slender habit and mode of growth. Mr. L. F. Henderson, of Portland, Oregon, who discovered it in 1881, near a branch of the Clackamas River called Eagle Creek, about thirty miles from Portland, reports it as growing in the fir forests in broad mats, its very long rootstocks running along near the surface of the ground, just covered by moss or partly decayed fir-needles, with a light addition of soil. This also would indicate the need of special care and treatment in its cultivation. In May, 1884, Mr. Henderson took great pains to procure roots for the Botanic Garden at Cambridge, which were received in good order, but which did not survive the next winter. If taken up, however, later in the season or very early in the spring, it is probable that with due attention to soil and shade there would be little trouble in cultivating it successfully. The accompanying figure is from a drawing by Mr. C. E. Faxon.

Sereno Watson