San Antonio del Mar,
Spjut & Marin 11185,
Apr 1990

Mesa Camacho,
N of Punta Canoas,
Spjut 11233, Apr 1990

Arroyo Sauces, between
Punta Blanca and Punta Canoas, Spjut & Marin 11438, Apr 1990

Bahía Santa María,
Spjut & Marin 11559,
Apr 1990

3-4 miles SW of El Rosario,
windy mesa, Spjut & Marin 12662, Apr 1993

El Marrón Ridge,
S of Punta Negra,
Spjut 9902, May 1986

General habit on mesa southwest of El Rosario

Ridge above Punta Baja,
Spjut 10261, Mar 1988

Niebla effusa is a lichen that is endemic to the Baja California peninsula, occurring along the Pacific Coast from near Rosarito to Colonet. It has a thallus characterized by sublinear interwoven branches that are terminally flattened, dilated and fringed with wide-spreading branchlets along an arched branch, although branchlets may also appear more erect and comb-like on horizontally branches that spread along the ground.

Niebla effusa perhaps produces the largest thalli on the planet in terms of weight and size, attaining more than 1 m in diameter with a weight of more than 1 kg. An example is shown in Spjut (1996, Plate 4C). Species of Usnea, and other pendant lichens, which may drape more than 1 m from tree branches, do not produce the weight found in species of Niebla. Niebla effusa is able to attain its large size by spreading over the surface of the earth in which its branches are not always confined to a holdfast.

Moreover, Niebla effusa dominates the terricolous lichen community, constituting much of the ground cover in a transitional coastal chaparral scrub on mesas between Colonet and Punta Baja. Associated terricolous species include N. arenaria, N. josecuervoi, N. juncosa var. spinulifera, N. palmeri, and N. pulchribarbara. The latter two are relatively rare, and distinguished by their secondary metabolites, sekikaic acid, and protocetraric acid, respectively, in contrast to salazinic acid in N. effusa. In this region, Niebla species seem to grow more on soil than rock because of the strong coastal wind as evident by the wind-swept appearance of the vascular flora. Young thalli of Niebla effusa can be seen initiating on bare ground between rocks, in contrast to related species arising from small stones in the same environment. The terricolous lichen community is in further contrast to the rock dwellers of the California chaparral and to the boulder and pebble Niebla communities further south, and to the sporadic occurrences of sand Niebla species found along bays, near beaches and on mesas.

Niebla effusa is not a tumble (“vagrant”) lichen, one that moves about as result of being taken up by the wind, as implied by Bowler and Marsh (2004), in contrast to N. arenaria and N. limicola that often occur near beach areas where they may be blown about. Occasional saxicolous variants of N. effusa are recognized to arise from a holdfast, or develop on rock as shown above; however, they may later spread beyond the rock (also evident in the same photo); these seem to occur more in the southern part of the range in Baja California.