FWS will designate critical habitat, if determined to be prudent and determinable, for four Florida Keys plants: the sand flax, Big Pine partridge pea, Blodgett's silverbush, and wedge spurge, pursuant to the Endangered Species Act of 1973, as amended. We are required to designate critical habitat, to the maximum extent prudent and determinable, concurrent with a listing determination for the species. FWS will develop a listing determination for these species as a separate rulemaking action (1018-AZ95). The sand flax is a perennial herb found in pine rockland, marl prairie, and adjacent disturbed habitats. The Big Pine partridge pea is found in pine rockland habitat in Big Pine Key. Blodgett's silverbush is a forb/herb found in sunny edges and gaps in pine rocklands, rockland hammocks, and coastal berm habitats. The wedge spurge is also found in pine rockland habitat, in sandy loam over limestone bedrock. All four of these plants occur in Dade (a narrow band from Miami southwest to the eastern portion of Everglades National Park) and Monroe (northern portion of Big Pine Key) Counties, Florida.