Lupinus cumulicola

Lupinus cumulicola, commonly referred to as sky-blue lupine, is a species of flowering plant endemic to the Lake Wales Ridge in the US state of Florida.

Habitat

It is native to the sandy, fire-dependent habitats of the ridge, primarily longleaf pine sandhill and scrub. However, it is capable of persisting in degraded habitats such as rangeland and roadsides, provided the frequency of disturbance is not too high.

Taxonomy

The lupine taxa of Florida have, as of 2024, been undergoing intensive reassessment. Lupinus cumulicola was, until recently, included under Lupinus diffusus which covered all Florida populations. However, recent work has shown that Lupinus cumulicola should be regarded as a separate species endemic to peninsular Florida.

Comparison with related species

Lupinus cumulicola is a member of the unifoliolate Lupinus species complex of peninsular Florida, a group of closely related taxa segregated from the historically broad concept of Lupinus diffusus based on morphological and geographic differentiation.

Within this complex, species are distinguished primarily by leaf pubescence (density and whether the green surface is visible), leaf proportions, floral characters (especially the banner eyespot), habit, and geographic distribution.

Lupinus cumulicola is characterized by its densely silky-pubescent leaves, which give the plant a silvery appearance and largely obscure the green leaf surface, along with its restriction to xeric sandy habitats of central Florida ridge and scrub systems.

It differs from related species as follows:

• Lupinus floridanus — leaves only moderately pubescent, with the green surface clearly visible; leaf blades typically more elongate; banner eyespot pale to cream-colored.

• Lupinus pilosior — similar in having dense pubescence, but typically with even more persistent and extensive hair coverage and often a more compact habit.

• Lupinus ocalensis — differs in leaf morphology, pubescence, and floral traits; geographically restricted to ridge systems of central Florida, especially the Ocala region.

• Lupinus westianus — generally more robust with broader leaves and distinct floral characteristics; restricted to southern Florida and the Florida Keys, and divided into two subspecies.

• Lupinus diffusus (sensu stricto) — more widespread outside peninsular Florida and differing in leaf and floral traits; many Florida populations formerly assigned to this species are now segregated into distinct taxa including L. cumulicola.

• Lupinus villosus — a more widespread southeastern species with densely silky, silvery foliage but typically larger and more robust, occurring primarily in longleaf pine sandhills and disturbed sandy habitats outside the central Florida ridge systems.

These differences reflect a radiation of closely related taxa adapted to xeric, fire-maintained sandy habitats of peninsular Florida, with Lupinus cumulicola representing a lineage distinguished by its consistently dense, silvery indumentum.

References