Lepidium oleraceum is a herb in the Brassicaceae

Brassicaceae

Brassicaceae, a medium sized and economically important family of flowering plants , are informally known as the mustards, mustard flowers, the crucifers or the cabbage family....

 family, endemic to New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. Its English common name is Cook's Scurvy Grass; Māori

Maori language

Māori or te reo Māori , commonly te reo , is the language of the indigenous population of New Zealand, the Māori. It has the status of an official language in New Zealand...

 names include Heketara, Nau and Ngau.
There are three recognised varieties:

• var. frondosum Kirk
• var. acutidentatum Kirk
• var. serrulatum Thell.

In New Zealand it is native to coastal areas of the North

North Island

The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...

 and South

South Island

The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...

 Islands, Stewart Island, the Three Kings Islands

Three Kings Islands

The Three Kings Islands or Manawa Islands are a group of 13 islands about northwest of Cape Reinga, the northernmost point of the North Island of New Zealand, where the South Pacific Ocean and Tasman Sea converge. They measure about 4.86 km² in area...

, the Snares Islands, the Chatham Islands

Chatham Islands

The Chatham Islands are an archipelago and New Zealand territory in the Pacific Ocean consisting of about ten islands within a radius, the largest of which are Chatham Island and Pitt Island. Their name in the indigenous language, Moriori, means Misty Sun...

, the Auckland Islands

Auckland Islands

The Auckland Islands are an archipelago of the New Zealand Sub-Antarctic Islands and include Auckland Island, Adams Island, Enderby Island, Disappointment Island, Ewing Island, Rose Island, Dundas Island and Green Island, with a combined area of...

, the Antipodes Islands

Antipodes Islands

The Antipodes Islands are inhospitable volcanic islands to the south of—and territorially part of—New Zealand...

 and the Bounty Islands

Bounty Islands

The Bounty Islands at are a small group of 13 granite islets and numerous rocks, with a combined area of , in the south Pacific Ocean that are territorially part of New Zealand. They are located between 47°44'35" and 47°46'10" S, and 179°01' and 179°04'20" E, southeast of the South Island of New...

.
Although this species was once widespread, it is now mostly restricted to off-shore rock stacks and islets.