Remy’s Scurvy Grass or Remy’s Pepperweed was described in 1890, it was endemic to the island of Hawai’i, the largest of the Hawaiian Islands, were it apparently was only ever known from a single site somewhere on the slopes of the Hualalai volcano. It was collected sometimes between 1851 and 1855, another collection from the year 1949 is thought to possibly also represent this species.
The species was given the status of a variety of Lepidium bidentatum Montin in 1969, and the photo below shows a variety of that species that is endemic to the Hawaiian Islands, the Hawaiian Scurvy Grass (Lepidium bidentatum var. o-waihiense (Cham. & Schltdl.) Fosberg).
Remy’s Scurvy Grass might have been nothing but a extreme form of another Hawaiian Scurvy Grass species, or it might have been an extremely rare endemic species, whatever case, it is now most likely extinct.
 F. R. Fosberg: Miscellaneous notes on Hawaiian plants – 5. Bishops Museum Occasional Papers 24(2): 1-24. 1869
The Obtuse-glanded Scurvy Grass was described in 1892, the species were known from two populations on the North Island of New Zealand: one at the coastline of the Waitakere Ranges, and another one on the Miramar peninsula on the southeastern side of the city of Wellington.
The first of these population disappeared around 1917, the other one from Wellington was last seen in 1950, thus the species is now considered extinct.
The species is furtermore known to have hybridized with a close relative, Cook’s Scurvy Grass (Lepidium oleraceum G. Forst. ex Sparrm.) with which it grew sympatrically at at least one site, Seatoun, a suburb of Wellington. 
For a very short glimpse of time this species was about to “rise from the dead” – seeds, collected from a specimen that had been collected in the late 1930s was sown in 1993, and it indeed begun to germinate!
However, this experiment did not succeeded because the seedlings died shortly after.
 P. J. de Lange; P. B. Heenan; G. J. Houliston; J. R. Rolfe; A. D. Mitchell: New Lepidium (Brassicaceae) from New Zealand. PhytoKeys 24: 1-147. 2013