Common Trees of Puerto Rico and the Virgin Islands

I
TREE SPECIES, DESCRIPTIONS AND ILLUSTRATIONS
TREEFERN FAMILY (CYATHEACEAE)
1. Helecho gigante, tree-fern Cyathea arborea (L.) 3. E. Smith
Tree-ferns, among the most beautiful plants of
tropical mountains, are common in Puerto Rico.
They are readily recognized as ferns by their lacelike
fern leaves unrollin from a coil at the apex
f
and by the absence of owers, fruits, and seeds,
while their slender unbranched trunks, leafy only
at the summit, qualify them 21s trees.
This species, the commonest of 5 or 6 kinds of
trunked ferns reaching tree size in Puerto Rico,
is characterized by : (1) slender unbranched
brown trunk, scaly but spineless, usually with
large oval leaf scars in the upper part and bearing
at apex a crown of about 10-18 large spreading
leaves; (2)' feathery (3-pinnate) leaves mostly
6-10 feet long, the thin blade divided 3 times,
endin in a lon pointed tip curved downward;
and 6) small f romvn ball-like masses less than
1/16 inch in diameter, borne on the underside of
some leaves and producing numerous powdery
spores.
A very handsome small evergreen tree to 30 feet
or more in lleiglit, with trunk 3-5 inches in diaine-
ter and stately crown of graceful leaves, ovate in
general outline. This species is spineless through-
out, though certain kinds have spin trunks and
leaf axes. There is no conspicuous iud, but usu-
ally 14 youna unrolling leaves, actually alternate
though crow&d.
A mature leaf has a light brown axis scaly at
base and many yellow-green secondary axes as
much as 2 feet Ion each bearing feathery taper-
P
ing branches less t an 6 inches long. The numer-
ous regularly arranged leaf segments are narrowly
oblong, 3/g inch or less in length, rounded at apex,
and with the minutely wavy-toothed edges turned
under. The thin segments are yellow green on
both sides. A dead leaf soon falls, leaving a large
oval scar.
Some older leaves bear minute brown balls or
bends (sori) in 2 rows on under surface of segments,
composed of numerolls spore cases (sporangia)
\vhich shed powdery masses of microscopic
spores. Under favorable conditions spores, like
seeds, develop into new plants.
Trunks of giant ferns differ from those of most
trees in several ways. The smootl~isl~ surface is
brown and scaly, often covered below with mnsses
of smaller plants, such as mosses, livenvorts, and
ferns, and with man small black roots projecting
from the enlarged g ase. Not divided into bark
28
and mood, the trunk does not grow in diameter.
There is a hard black outer layer 4/s inch or more
in thickness and a central white soft pith containing
a ring of brown bundles which serve for conduction
and strength.
Thouglx not solid woocl, the hard trunks are durable
and resistant to decay and termites. Elsetvhere,
trunks of tree-ferns have served as posts,
fmme~vorks of houses, supports for vanilla plants
ancl other orchids, and as wnter bars for drainage
along mountain trails. The Carib Indians used
the stems to preserve and carry fire, ~\-hich can be
maintained for hours \\-itllout snroke or flames..
These lusuriant ferns seem to thrive following
opening of the areas and construction of mountain
roads, often growing abundantly along the cut
roadside banks. One of the most easily accessible
areas for viewing these odd plants is alollg the
high-ay crossing the Luquillo Mountains.
Though very ornamental in their native mountains,
tree-ferns seldom are cultivated in Puerto
Rico. It is reported that small plants can be transplanted
successfully and garden-grown in moist
regions, even at sea, level.
In lower and upper mountain forests of Puerto
Rico growing as a small understory tree and esa
y common in open areas such as ravines,
geci anks, l1 and roadsides. Also recorded from St.
Thomas and Tortola, now probably rare on the
latter and not observed there in 1954.
Pml~rc FORES~.--Carite, Guilarte, Luquillo,
Maricao, Toro Negro.
RAXQE.-Greater Antilles, St. Thomas, Tortola,
and Lesser Antilles in Saba, St. ICitts, Nevis,
Guadeloupe, Dominica, Montserrat, Martinique,
St. Lucia, St,. Vincent, and Grenada. Also in Trinidad.
Recorded as rare in lowlands of eastern
Mexico.
OTI~ER COJLJfON NAJIEB.-~~~~C~O arbbreo, helecho,
palmilla, camadn, cam~roncillo (Puerto
Rico) ; camarrin, llelecllo lirbol, palmera sin espinas
(Cuba) ; tree-fern (Englislx) .
Several species of trunked ferns of this and related
genera (Hemitelin and AZ-vophiln) are native
in mountain forests of Puerto Ricq t.hough uncommon
to mi= and usually not rencll~ng tree aze. A
related large tree-fern wit11 small spines on the
trunk is Cyathea hm'ttoniann Maxon. Another
largm tree-fern with leaves only tm-ice pinnate (2pinnate)
and with spines is C. pubescens Mett.