Haleakala rises above the belt of warm trade winds into the cold, dry
climate of the Alpine Zone. Temperatures at night may drop below
freezing even in the warmer part of the year; the growing season is
short and life is severe. The sparse plants that can live here crouch
closely to the ground, diffusing or forming compact rosettes. All they
have in which to grow are porous rocks and loose cinders that cannot
hold moisture, lack organic matter, and do not yield a firm base for
rooting. Species extending to lower elevations are here depauperate from
wind and cold, although elsewhere they may attain a sturdy stature, even
tree-size. Few seedlings are seen; individuals whose life span has
finished remain conspicuous in death. Neither trees nor mats of shrubs
are seen, but mosses and lichens find this Alpine desert to their
liking. Oddly enough, one looks in vain for brilliant blossoms, such as
one has come to expect in the high Sierra and the Rockies. The summit is
a biological island on an oceanic island which, geological evidence
indicates, never was part of a continent. The Hawaiian Chain was never
near land of appreciable height and size.
How the Alpine plants came to Hawaii is uncertain since they have
descended from ancestors so remote that past relationships are vague.
The great Swedish botanist, Carl Skottsberg, believes that they are
derived from a flora that grew on summits higher than any that exist
today. Such assumption adds to the problem, as little else leads one to
believe that elevations ever significantly exceeded 14,000 feet, i.e.,
the highest that exist today. In a report for the Fifth International
Botanical Congress (Proceedings, pp. 91-97, Cambridge, 1931), Skottsberg
listed 13 species found exclusively in the Alpine Zone, all of which are
endemic, native to no other place than Hawaii's highest volcanoes. Three
other species listed as occurring in the Alpine Zone extend their range
downward into the next lower Subalpine Zone, for which he has listed a
total of 23 species, 20 of which he labels endemic. These adjoining
zones are not sharply delimited, but blend into each other at 9,000
feet.
As elevation decreases and conditions for growth become better, the
number of plant species increases. The Subalpine Zone with lower limits
just above the park entrance has some of the most interesting plants
found in the islands. Trees are absent but some of its shrubs extend
their range to lower elevations and grow big, sometimes even to
tree-size. Most Subalpine plants have small leaves or leaflets,
indicating that lasting moisture is still scant. Occasional snowfall
seldom remains long and never piles into drifts, which would conserve
moisture.
Most of the interior of the crater is bare or thinly covered with
vegetation. The uncongenial climate of the summit spills into it and
extends throughout its length, though the elevation is much lower.
Extensive aa flows, ash, and cinder cones cover the floor. Yet the
crater has perhaps become best known through the presence of one of its
plants, the silversword. Also, the lips of Koolau and Kaupo Gaps are
botanically distinctive in contrast to the barreness elsewhere. This
results from the fog and rain that sweep through them in late morning,
only to dissolve upon mixing with the warmer air inside. As the day
progresses, clouds push further and further inward, until, rarely, the
whole depression may become filled. Koolau especially is a
treasure-trove for the plant-lover. Below 6,000 feet, quite outside the
park, it becomes impenetrable jungle surpassed only by that in Kipahulu
Valley, a few miles east. Kaupo Cap is comparatively dry, but it
supports a sparse scrub cover of great interest. The lower parts of
Kaupo Valley are grazing land. Paliku is the only place within the park
in which vegetation is lush. As it climbs Leleiwi Pali, Halemauu Trail
is bordered by OHELO and ferns, among them AMAUMAU which is pleasing to
the weary hiker's eye.
In the northwestern angle of the park not far from the inn, Nianiau
Crater has had a renowned floral character and history. Today it is
overgrazed and drab. Dr. Joseph Rock, Hawaii's famed dendrologist,
discovered a curious tree _lobelia_, _Clermontia haleakalensis_, growing
within it. He happily described the plant as "antediluvian in
appearance." This most primitive member of a distinctive Hawaiian floral
group had a robust trunk from which clumsy, stubby branches shot off,
each crowned with a feather-duster of long, thick, strap-shaped leaves
like some pompous dictator's headdress. MAMANE and AKALA grew thickly
around it; rarer associates included tree geraniums, _Neurophyllodes
sp._, with flowers like violets, tree _Railliardia_, shrubby Hawaiian
buttercups, and greensword, _Argyroxiphium virescens_, that is
threatened with extermination by grazing to an extent greater than of
its relative, the silversword.
[Illustration: BISHOP MUSEUM, J. F. ROCK COLLECTION
Clermontia Haleakalensis.]
Even though they are outside the park, some plant communities on the
outer slopes of the mountain should be mentioned, because they are
related to park forms and carry a compelling interest. The trail from
Olinda to Waikamoi is through a transition forest between the wet and
the dry that once drew botanists from many parts of the globe. It is now
overgrown with foreign weeds, so that native shrubs survive only here
and there. The mountain forests above Olinda have all been destroyed and
are replaced by plants from faraway lands.
Although it now lies devastated by change, one of the richest botanical
regions in Hawaii comprises the forbidding lava fields of Auwahi on the
southwest slope of Haleakala. Fifty species of native trees once thrived
in its fabulous mixed forests. The only known specimen of Maui
hibiscadelphus, _H. wilderianus_, a relative of the hibiscus, was found
here. It had a curved corolla that opened only slightly at the top. Its
congener, _H. giffardianus_, once equally rare, still survives in Kipuka
Puaulu at Kilauea, where a few vigorous plants, started by air-layering,
receive tender care from the National Park. The last known Maui specimen
of MAHOE, _Alectryon macrococcus_, grows in an Auwahi gulch. This tree
has large double fruits (_mahoe_ means _twins_) that split open to
expose a shiny, chestnut-brown seed clasped in a brilliant scarlet aril.
The ALANI, _Pelea multiflora_, of the lava fields is festooned with a
lichen, _Usnea australis_, that appears to prefer it to all other trees.
Haleakala sandalwood, _Santalum haleakalae_, with attractive red flowers
grows to be a tree 25 feet tall. Other famous native trees include
'OHE'OHE, _Tetraplasandra kauaiensis_; 'OHE, _Tetraplasandra meiandra_;
A'E, _Fagara_ sp.; 'ALA'A, _Planchonella auahiensis_, with golden
fruits; HO'AWA, _Pittosporum terminalioides_; OLOPUA, _Nestegis
sandwicensis_; A'IA'I, _Pseudomorus sandwicensis_; MEHANE, _Antidesma
pulvinatum_; and KAUILA, _Alphitonia ponderosa_, whose hard and durable
timber was used in sacred structures.
Many unusual plants occur in the steep valleys to the north and east
outside the park. Since the dense jungles in which they grow are
inaccessible except to hardiest botanists, they are seldom seen. Here
grow 'APE'APE, _Gunnera petaloidea_, a plant with geranium-like leaves
three or more feet in diameter; a delicate, rare, native begonia,
_Hillebrandia sandwicensis_; several exquisitely flowering lobelias. The
summit bogs on Kukui and Mt. Eke in West Maui have a curious,
distinctive flora that includes three species with origins ascribed to
the Antarctic: _Orebolus furcatus_, a sedge; _Acaena exigua_ of the Rose
Family; and _Lagenophora mauiensis_, a composite.
[Illustration: BISHOP MUSEUM, J. F. ROCK COLLECTION
Tetromalopium.]
[Illustration: BISHOP MUSEUM, J. F. ROCK COLLECTION
Begonia.]
The Haleakala road is the easiest way to reach elevations above 7,000
feet in Hawaii. The lower mountain slopes up which it winds were once
clothed with fern jungles that yielded with altitude to dry forest. All
is now altered. Extensive grasslands and eucalyptus groves today leave
the lasting impression on the visitor. Even on the heights, cattle,
goats, introduced plants, insects, and other agents have wrought
permanent change. Rare and interesting forms of native life have been
exterminated or are well on the way to extinction. The National Park is
trying hard to save what is left of the native cover within its
boundaries and to restore the former scene wherever it is possible to do
so.
[Illustration: BISHOP MUSEUM, J. F. ROCK COLLECTION
'Ape'ape.]
Plants of the distinctive Haleakala environment show differences, some
slight, some considerable, from close relatives elsewhere. Examples are
the OLAPA at Paliku, the silversword, and the KUPAOA. The differences
have been fashioned by combinations of factors. The unstable, permeable
ash and cinders have scant soil and little available mineral matter.
They cannot hold water nor do they yield secure anchorage. The effects
of winds, isolation, exposure, and nature of terrain are reflected by
the distorted shapes. Silversword, _Artemisia_, _Bidens_, and many other
plants well show adaptation to peculiar environment. Why are some
species found nowhere else? How did the plants get here in the first
place and how have they changed with the passing of time? What has been
the impact of exotics? What use did the Hawaiians make of the plants? To
the hurried and casual visitor, the flora of Haleakala may appear drab
and uninteresting. With better acquaintance, it becomes a stimulating
study indeed.