Dialypetalanthus Fuscescens Kuhlm. (Dialypetalanthaceae): The Problematic Taxonomic Position of an Amazonian Endemic

23 Pages·1997·15.6 MB·English

by  Frederic Piesschaert

DIALYPETALANTHUS
FUSCESCENS KUHLM.
(DIALYPETALANTHACEAE):
THE
PROBLEMATIC
TAXONOMIC
OF
POSITION
AN AMAZONIAN
ENDEMIC
1

Volume Number
2
84, Piesschaert 203
et
al.
1997
Dialypetalanthus fuscescens from Amazonia
The wood
scope. In order show the thickenings of the inner fluted toward the base. is light but ex-
to
used house construc-
tangential walls of the exotestal cells, the outer tan- tremely hard. It is locally for
&
we
gential walls had be removed. Therefore, boiled tion (Rizzini Occhioni, 1949), but as far as
to
know economic
seeds were transferred to a 3:1 mixture of alcohol it has little value.
96% 99%
and 24 Afterward
acetic acid for hours.
The
3% Leaves. simple leaves are decussately ar-
they were put a aqueous mixture of sulphuric
in
The
ranged and have blades with entire margins.
from
acid 50°C 10 hours (modified
at for at least
cm) and
petiole well developed (0.6-3.5 shallow-
Braune Remaining specks of were is
et 1967). dirt
al.,
The
sulcate above. blades are broadly elliptic
ly
removed by
ultrasonication.
suborbiculate
The methods used and breaking (L/W-ratio 1.5:1), elliptic (2:1), (1.2:
for acetolysis
by Huysmans to narrowly (2:1) or widely obovate (1.2:1)
pollen grains are discussed in detail 1),
(sometimes asymmetric), with a shortly acu-
Wood were slightly
anatomical sections pre-
et al. (1994).
pared as described by Jansen et (in prep.).
al.
neate slighdy decurrent base (terminology follow-
to
X
ing Hickey, 1988); they are (2-)6-17(-20) (1-)
Results
4—11(— cm. The leaf venation pinnate and
14) is
VEGETATIVE STRUCTURES
camptodromous. Hie veins, especially the midvein
1A), are prominent on the abaxial side of the
Habit. Dialypetalanthus fuscescens is a large, (Fig.
The divergence angle between primary and
blade.
35°
(because of secondary veins is about in the center of the
usually has a fibrous
smaller). soft,
It
phellogen blade and gradually rises toward the base of the
the formation of several concentric lay-
The up
The trunk veins are detectable to the order.
red cinnamon-colored bark. is leaf. fifth
ers),
to
la
in size (upper ones much larger than the short, tain silica-bodies (Fig. 4G, H). The perforation
tri-
angular lower ones; Fig. Anatomically, the stip- plates of the vessels are simple, bearing a single
2).
ules have a characteristic adaxial epidermis, con- elliptical to almost circular opening (Fig. 5A). The
The
sisting of thickened Scattered through the vessel-ray pits are simple (Fig. 5B). intervessel
cells.
homogeneous chlorenchyma are numerous small pits are alternately arranged and vestured (Fig. 5C).
phloem
vascular traces that are surrounded by fibers. Riz- Internal is absent.
and
zini Occhioni (1949) recorded occasioned par-
REPRODUCTIVE STRUCTURES
acytic
The bloom
Wood, anatomy. The wood of Dialypetalanthus Inflorescence. of Dialypetalanthus is
shows
indistinct growth rings (probably reflecting
The
the precipitation cycle), marked by a transition large inflorescences. inflorescence of Dialype-
Kuhlmann
from thin- to thick-walled fibers. The fibers are sep- talanthus (Figs. 6-8) was described by
tate (Fig. 4C) and have simple pits in vertical rows (1925) as paniculate and racemose. Rizzini and Oc-
(Fig. 5D) (libriform fibers sensu Baas, 1986). The chioni (1949) and Hutchinson (1959) also indicated
wood diffuse-porous. The vessels are solitary or was a panicle. According to Weberling (1992), a
is it
by on
arranged in short radial rows (2-8 cells) (Fig. 4D, panicle is characterized terminal flowers its
E). In young wood, close to the pith, the radial main axis and side branches. Thus, a panicle is a
how-
The determinate inflorescence. Dialypetalanthus,
vessel rows are often longer. outline of the sol-
itary vessels rounded 4E), although the ever, does not have a terminal flower but a terminal
(Fig.
is
may
smaller vessels are often compressed between the bud that at first sight be confused with a single
bud
larger ones. Axial parenchyma present and oc- terminal flower. Dissection of the terminal re-
is
The meristem where acropetal inception
curs as scanty, paratracheal strands (Fig. 4B). veals a floral
width of the rays varies from (l-)2 to 6 cells (Fig. of lateral flowers occurs (the flowers in the most
4A); may exceed 100 In radial terminal zone seem to be poorly developed) (Fig.
their height cells.
The
have inflorescence of Dialypetalanthus thus
sections, the procumbent body-ray cells a 7). is
margin of one or often several layers of square cells indeterminate, contrary to a panicle. Dahlgren and
Thome
(Fig. 4F). Sometimes a mixture of procumbent and (1984) provided the first correct illustration
more or less square cells occurs. The rays are vis- of the inflorescence but did not describe it. Cron-
was
ible to the naked eye as clear, narrow, parallel quist (1981) the first to correctly call the Di-
a More
lines. The pith and the rays contain very small cu- alypetalanthus inflorescence thyrse. specif-
occur a frondobracteose, heterothetic,
bic to prismatic crystals; navicular crystals ically, it is
as well. The septate fibers as well as the rays con- indeterminate thyrse with opposite branches (Fig.
206 Annals the
of
Garden
Missouri Botanical
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Garden
Volume Number
2
84, Piesschaert 209
et
al.
1997