flora neotropica - CNCFlora

Rare Species 3
Loreto Department, was also largely based on thick; inner epidermis of ii developing into the
the "Flora Neotropica" account.
endothelium which directly borders the embryo
The monographs of the 61 African species of sac and accumulates starch grains; micropyle
Chrysobalanaceae have also allowed an inter- formed by both integuments. Fertilization poesting
comparison between the two continents rogamous; endosperm formation of the Nuclear
(Letouzey & White, 1976, 1978a, 1978b; White, type; seed exalbuminous. Young seed coat com-
1976). This also led to the removal of the African posed of both testa and tegmen; exotegmen fispecies
with a staminal ligule from the neotrop- brous; exotesta one-layered, composed of cuboid
ical Acioa to a distinct genus Dactyladenia Welw. tanniniferous cells; endotesta a few layers thick
(Prance & White, 1979). Likewise the species of composed of unspecialized small cells; micro-
Malesian Chrysobalanaceae have recently been testa 30-50 cells thick in C. icaco, composed
revised and their relationships to neotropical taxa mostly of vessels, 3-4 layered and lacking vasare
now better understood (Prance, 1979b, 1987, cular tissue in L. michauxii. Mature seed mein
press). Finally, a detailed worldwide treatment sotestal.
of the genera of Chrysobalanaceae (Prance & The embryological data given above show that
White, 1988) has been completed.
there is little difference between the species studied.
The Chrysobalanaceae differ from the Ro-
EMBRYOLOGY
saceae, to which it has frequently been related,
in the tenuinucellate ovule, the very small nu-
At the time of the 1972 monograph little de- cellus that disintegrates early, and the presence
tailed work had been done on the embryology of of an endothelium. Tobe and Raven conducted
the Chrysobalanaceae. Recently Tobe and Raven their investigation to consider the possible re-
(1984) studied the embryology of three neotrop- lationship of the Chrysobalanaceae to the Myrical
species-Chrysobalanus icaco L., Licania tales, but concluded that it is embryologically
apetala (E. Mey.) Fritsch, and L. michauxii quite different from that well-defined order. They
Prance. This has at least provided some basic proposed a relationship to the Theales, which
data for the tribe Chrysobalaneae. The most im- share with Chrysobalanaceae a tenuinucellate
portant embryological features are given below. ovule, a small disintegrating nucellus, an endo-
Anthers tetrasporangiate, the walls five layers thelium, Nuclear-type endosperm formation, and
thick, formation of the Basic type; epidermis an exalbuminous seed. However, the Theales difpersistent
and often tanniniferous, endothecium fer from Chrysobalanaceae in their one-celled
fibrous, the two middle layers ephemeral, the ovule, archesporium, an Allium-type embryo sac,
tapetum glandular with two-nucleate cells. Cy- and persistent antipodal cells. In their argument
tokinesis in the microspore mother cell simul- Tobe and Raven misrepresent the Chrysobalanataneous;
microspore tetrad usually tetrahedral ceae as lacking stipules. Since there are major
and occasionally decussate; pollen grains two- embryological differences between the Chrysocelled
when shed. Ovule anatropous and tenui- balanaceae and both the Rosales and Theales, it
nucellate, the nucellus very small; all archespo- seems unlikely that the family is any better placed
rial cells developing directly into megaspore in the Theales than in the Rosales and a more
mother cells, undergoing meiosis; megaspore definite placement can only be made after contetrads
linear; chalazal megaspore functional, de- siderable data are obtained from other fields, as
veloping into a modified type of the Polygonum- well as embryological information from a much
type embryo sac; mature embryo sac four-nu- wider range of Chrysobalanaceae, instead ofjust
cleate, comprising an egg, two synergids and a three species in the two most closely related gencentral
nucleus which is probably triploid; an- era.
tipodal cells absent from the beginning, hypostase
differentiating in Chrysobalanus but not Li-
RARE SPECIES
cania; the nucellar tissue soon disintegrating
except the megaspore and embryo sac. Ovule At the 1986 meeting of the Organization for
bitegmic, the inner integument (ii) and outer in- Flora Neotropica it was recommended that
tegument (oi) initiated desmally, the ii up to five monographers comment on and point out rare
or eight cells thick and the oi more than five cells and endangered species in their groups. Although