The Geography of Phytochemical Races

5.2 Nonvascular Plants 223
different microhabitats, referring to Kershaw’s (1985) discussion of the effects of
microhabitat differences on lichen physiology.
5.2.3 Thamnolia vermicularis (Icmadophilaceae)
Thamnolia vermicularis is an arctic-alpine, fruticose, soil-dwelling lichen that
enjoys a very wide distribution. The species consists of two chemical strains, one
predominantly found in the Northern Hemisphere and the other in the Southern
Hemisphere, with most populations from intermediate regions exhibiting intermediate
chemical types. Sato (1965) showed that the southern strain accumulates
thamnolic acid [403], whereas the northern strain is characterized by two
compounds, squamatic acid [404] and baeomycic acid [405]. Populations from
Greenland, Novaya Zemlya, and Svalbard exhibited only the northern profi le. Two
populations from South America exhibited only the southern type, while collections
from New Zealand showed “nearly pure” southern type.
5.2.4 Lobaria pulmonaria (Stictaceae)
Lobaria pulmonaria (L.) Hoffm. var. meridonalis (Vain) Zahlbr. is a widespread
lichen characterized by a lobed structure similar in appearance to alveolar tissue. As
González et al. (1994) pointed out in their introduction to a discussion of the chemistry
of this lichen, its specifi c epithet refl ects its use as a treatment for pulmonary
tuberculosis following the Doctrine of Signatures. The varietal name was appended
much later to specimens collected in the Philippines.
The present chemical study was done on plants collected from Pinus canariensis
growing at several sites in the Canary Islands. The major constituents were identifi
ed as the depsidones stictic acid [406], norstictic acid [407], and constictic
acid [408] (see Fig. 5.4 for structures 406–411). All of these compounds have
been identifi ed from Asian plants. Lesser components from the Canary Island
plants were identifi ed as methylstictic acid [409], hypostictic acid [410], and
cryptostictic acid [411], all of which were reported for the fi rst time in that paper
(González et al., 1994). Those workers suggested the possibility that these latter
three compounds may be “found randomly in this species …” and thus have no
taxonomic signifi cance. They left the door ajar, however, recognizing that this
array of pigments may be “the consequence of the geographical or ecological
distribution of the area where the taxon under study was collected.”
5.2.5 Bazzania trilobata (Lepidoziaceae)
The bryophyte literature provides many examples of disjunct distributions often
involving sites that defy easy explanations for their existence. Nonetheless, they