Geography of Vegetabilia
While taiga forest
looks similar in Alaska and Patagonia (South America), a closer look will
immediately reflect that species, genera and even families of plants are quite
different. As an example, both Alaska and Patagonia forests in-clude large
conifers, but while in Alaska we frequently see members of Pinaceae family like
spruces (Picea) or firs (Abies), in Patagonia these trees are
absent and “replaced” with superficially similar trees of Araucariaceae and
Podocarpaceae families of conifers. Analogously, Arizona desert is similar to
African Kalahari but while American deserts are rich with cacti, similarly
looking African plants belong top completely different group, succulent spurges
(Euphorbia). The ef-fect of these
differences on the botanically educated traveler is a bit similar to the
nightmare when you first see a familiar thing but approach it—and realize that
this is something completely alien and strange.
These floristic differences are due to the
various geological and biological histo-ries of these places. Plant biogeography studies them,
explains them and creates the floristic
kingdoms classification (Fig. 9.2) which
takes into account not eco-logical but taxonomical (phylogenetic) similarities
There are only five
Holarctic Most of North America and temperate Eurasia. Holarctic kingdom
islargest, it covers two continents and most of Northern hemisphere. Typical
representatives are pines (Pinus) and
South American From South Florida to Patagonia and Antarctic islands. Aroids(Araceae
family) and bromeliads (Bromeliaceae) are very common South American groups.
African Excluding Mediterranean Africa (very north of the continent).
Africanacacias (Senegalia) are common
to the most of savannas there.
separate the southern tip of Africa into smallest Cape floristic kingdom which has multiple endemic plant genera
(likekolkol, Berzelia) and even whole
Indo-Pacific From India to pacific islands including Hawaii. This kingdom
isespecially rich of orchids (Orchidaceae); tropical pitcher plants (Nepenthes) grow only there.
Australian Australia, Tasmania and New Zealand. Numerous specific plantgroups,
including Eucalyptus, Banksia and many others.
Every plant group has
a specific range—the area of
distribution. There are mul-tiple common ranges, e.g., circumpolar (groups
distributed across North Pole, both in North America and Eurasia, like spruces,
Picea) or Gondwanian (groups
distributed in the South Africa, Australia and South America, like protea
family, Proteaceae). Sometimes, there are disjunctions
(breaks in range); a typical expla-nation for the disjunction is long-distance
dispersal (like for ispaghula, Plantagoovata
in California and West Asia) or extinction in the connecting places (like
fortulip tree, Liriodendron in China
and Atlantic states).
Recently, many plants
became invasive after being
introduced willingly (e.g., as forage plants) or accidentally (e.g., with seeds
of other plants). These plants (like Eurasian spotted knapweed, Centaurea stoebe in North America, or
North American box elder, Acer negundo
in Eurasia) are often noxious since
they tend to destroy the native vegetation.
It is frequently said
that humans stated the new epoch of Earth life, homocene—era of Homo sapiens
dominance, homogenization and great extinction of the flora and fauna. We need
to stop that!