Aspidotis densa

Aspidotis densa is a species of fern known by the common name Indian's dream. It is native to western North America from British Columbia to California to Wyoming, as well as parts of eastern North America including Quebec.

Aspidotis densa
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Class: Polypodiopsida
Order: Polypodiales
Family: Pteridaceae
Genus: Aspidotis
Species:
A. densa
Binomial name
Aspidotis densa
(Brack.) Lellinger, 1968
Synonyms

Cheilanthes siliquosa
Cryptogramma densa
Onychium densum
Pellaea densa

A. densa grows in rocky areas; in California it is often a member of the serpentine soils flora on rocky mountain slopes, well-drained but seasonally moist.

This fern has leaves on long petioles, with the blade occupying less than half of the total length of the leaf when including the petiole. The fertile and sterile leaves may look alike or slightly different. The leaf blade is triangular and composed of many leaflets which are subdivided into untoothed segments. The segments are lined with sori over which the edges of the leaf are folded to form a false indusium.

Aspidotis densa develops on crevices and exposed rocky outcrops in mossy cracks, and over time creeps to fill in every fissure, creating well-established colonies in the outcrop. They may exhibit frond dimorphism, that is, the sterile fronds are shorter and pinnae broader than the fertile, which rise above on long, wiry petioles. The pinnae of the fertile fronds are very narrow and lace-like [4].

Height: 2-4 in. Width 6-12 in.

As ecologic indicator

Aspidotis densa is a regional ecologic indicator on areas where ultramafic rocks are patchy, such as the Klamath Mountains of northern California and southwest Oregon, the areas of serpentine soil can be clearly seen as sparsely covered areas or open forest bounded by closed forest on the non-ultramafic soils [1].

Aspidotis densa at Icicle Canyon, Chelan County Washington

Phylogeny

Relationships between vascular plants with an emphasis on the ferns as summarized from morphological and molecular phylogenetic analyses. Kenrick and Crane (1997) summarizes the results of previously published studies[2].

For a complete fern family phylogeny see Smith et al. (2006) [3].

References
  1. Alexander, Earl B., Roger G. Coleman, Todd Keller-Wolf, and Susan P. Harrison. Serpentine Geoecology of Western North America. Oxford New York: Oxford University Press, 2007. Print
  2. Kenrick, P., and Crane, P. R. (1997). The Origin and Early Diversification of Land Plants: A Cladistic Study. Washington, DC: Smithsonian Institution Press.
  3. Smith, A. R., Pryer, K. M., Schuettpelz, E., Korall, P., Schneider, H., and Wolf, P. G. (2006). A classification for extant ferns. Taxon 55, 705–731. doi: 10.2307/25065646
  4. Cullina, William. Native Ferns Moss and Grasses. New York, New York: New England Wild Flower Society, 2008. Print.
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