Turritis glabra

Plants usually have several erect, usually unbranched stems which are grey in the lower parts with a covering of simple hairs, but green and glabrous (hairless) above.

[4] The leaves occur in a basal rosette initially, and later grow alternately on the main stem and branches.

[4] The basal leaves are usually covered in hairs (pubescent) on the upper surface, but in rare cases they may be hairless.

[2] Authors such as Hervé Maurice Burdet, James Cullen, and František Dvořák (1921–2016) maintained that the lack of white to purple flowers, not having seeds arranged in a single row in the pod like peas (uniserrately), and not having flattened fruits distinguishes the species in Turritis from Arabis.

Botanists maintaining the contrary position such as Reed C. Rollins and Ihsan Ali Al-Shehbaz point to the ambiguous characteristics of some individuals in Turritis glabra and what they consider more critical features such as similar seed-coat anatomy and chemical similarities such as fatty-acid composition and glucosinolate content.

[3] The genus name Turritis comes from Latin for tower as a reference to the narrow growth of the plant with the leaves and fruits upright and overlapping.

[2] In North America POWO lists it as native to all parts of Canada with the exceptions of Newfoundland and Labrador, Nova Scotia, Prince Edward Island, and Nunavut.

[1] Finally Plants of the World Online lists it as introduced to the Australian states of New South Wales and Victoria.

The flowers are cream or white, with 4 petals.
The fruit is a long, narrow silique with two rows of seeds in each valve.
Illustration of Turritis glabra from Flora von Deutschland, Österreich und der Schweiz 1885