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Continue SE across the lawn past the South wall of Avila Center toward the large and conspicuous late to leaf out European white poplar (Populus alba L.) (Fig. 9-1). This introduced tree may also be struggling a bit in our climate, providing good substrate for several lichens.

Fig. 9-1. White poplar in early Spring.

Most striking are the orange colonies, these are not the rock inhabiting Rusavskia, but Xanthomendoza species which prefer bark and have more finely divided lobes. Two Xanthomendozas are present: one with apothecia is X. hassiana (Fig. 9-2, blue pin) and the one covered in fuzzy soredia is X. fallax (Fig 9-3 yellow pin).

Fig 9-2 Xanthomendoza hassiana with orange apothecia, 2x magnification
Fig 9-3 Xanthomendoza fallax with clusters of soralia, at 2x magnification. The soralia at even higher magnification suggest birds' nests, hence the common name bird's nest lichen.
Fig. 9-4. Specimen of Ramalina (stiff thallus, unlike soft Evernia mesomorpha)
Fig. 9-5. Candellaria concolor.
Fig. 9-6. Phaeophyscia again
Fig. 9-7. Difficult to identify crustose lichen on the white poplar bark. Reproductive structures are likely perithecia (flask shaped structures burried in the thallus of the lichen).

To continue the walk, turn left on the paved road (later paved path blocked to vehicles - Fig. 9-8) and up the hill back to the main campus.

Fig. 9-8. View of the path back to the main campus, past sudent residences and physical plant workshop. Continue all the way to Braun building central enclosure/courtyard.

On campus turn left in front of the library, toward Agora Circle, the bus stops and main campus entrance. Opposite the sign for "Security" is the main (SW) entrance to the Braun Building, enter the Braun Building.