Mt. San Jacinto Summer 08
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Mt. San Jacinto August 2008: Part 1
   Part 1     Part 2     Part 3     Part 4 
W.P. Armstrong, 1 August 2008
Index Of Wildflower Pages On Wayne's Word
  Wayne's Word Page On Mycotrophic Wildflowers  

Grossulariaceae: Ribes montigenum (Mountain Gooseberry)

Photographed in Round Valley

Grossulariaceae: Ribes roezlii (Sierra Gooseberry)

Photographed in Tamarack Valley

  Mt. Currant (Ribes nevadense) On Palomar Mountain  
See Gooseberries & Currants In San Diego County

Apiaceae: Sphenosciadium capitellatum (Ranger's Buttons)

Philadelphaceae: Philadelpus microphyllus (Little-Leaf Mock Orange)

Pinaceae: Pinus flexilis (Limber Pine)

  Conifers Of The Palomar College Arboretum (1)  
Conifers Of The Palomar College Arboretum (2)

Pinaceae: Abies concolor (White Fir)

  The Santa Lucia Fir (Abies bracteata)  

Lycoperdales: Puffballs of the genus Lycoperdon

  More Puffball Images On Wayne's Word  

Rhizocarpaceae: Rhizocarpon geminatum

The genus Rhizocarpon is commonly known as map lichens because the colonies often resemble continents on a map. This is best exemplified in R. geographicum.

  See Map Lichen (Rhizocarpon geographicum)  
See Rhizocarpon disporum resembling a Map

According to Tom Nash and Bruce Ryan (Lichen Flora of the Greater Sonoran Region, Volume 2, 2004) Rhizocarpon geminatum has two spores per ascus. Although the specific epithet "disporum" refers to two spores per ascus, this species has only one spore per ascus. The oval spores are 48-78 micrometers long, compared with 30-65 micrometers for R. geminatum. The specific epithet "geminatum" is appropriate for this species because it refers to "twin" spores inside each ascus. I have undoubtedly misidentified the latter species for many years! R. geminatum grows on shaded granite boulders of the cool subalpine zone on Mount San Jacinto. The specimen in above photo was growing at approximately 9,000 ft (274 m) elevation. It has an enormous worldwide distribution, including western and northern North America, Greenland, Europe and South America.

Magnified view (400x) of hymenial layer of Rhizocarpon geminatum showing transparent fungal filaments (paraphyses), two brown, muriform ascospores within a transparent sac-like ascus. Because of the viewing angle, the left ascus appears to have a single large spore; however, it actually has two overlapping spores. Because of the low depth of field, it is difficult to distinguish the two spores without focusing up and down on them. This is especially true when the spores are tightly appressed to each other The closely-related R. disporum has one spore per ascus. Photographed through Olympus compound microscope with Sony V-3.

Magnified view (400x) of two asci of Rhizocarpon geminatum.

Note: I originally thought the following images from the Sierra Nevada were Rhizocarpon disporum; however, the magnified view shows two spores per ascus and this species typically has one spore. Therefore, the microscope images are undoubtedly the closely related species R. geminatum.

Rhizocarpon geminatum (previously labeled R. disporum) Left: Close-up view of lichen growing on a granitic outcrop in the Sierra Nevada of California. The thallus of this crustose lichen consists of numerous gray (tan), convex (bullate) areoles (similar to worts) scattered over a black hypothallus (prothallus) without algae. It superficially resembles light colored bumps on a black background. The black apothecium (red arrow) is similar to Lecidea without a thalline rim (i.e. without algal cells). Right: Microscopic view of an ascus (red arrow) containing two large muriform spores. Each spore is 30 to 50 micrometers long (1/500th of an inch). The brown spores are partitioned into smaller sections like the squares of a Hershey's® chocolate bar.

  Lichen Images On Wayne's Word  

Map lichen (Rhizocarpon geographicum).

Caloplaca species. This might be C. ignea or possibly C. saxicola.

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