作 者 ：Zhang Zhi-Yun, Lu An-Ming
期 刊 ：植物分类学报 1989年 1期
关键词：交让木科气孔花粉形态系统位置；
Keywords:Daphniphyllaceae, Stoma, Pollen morphology, Systematic position,
Abstract:
The present paper deals with the systematic position of Daphniphyllaceae. The
genus Daphniphyllum was first described by Blume in 1826 as a member of Rhamnaceae. In
1858 Baillon removed it to the tribe Phyllantheae of Euphorbiaceae, while Müller (1869) raised
this genus to the rank of family, Daphniphyllaceae. Although Müller’s treatment has been ac-
cepted by most botanists, including the present authors, its systematic position has been debated.
The first aim in our studies on the cladistics of Hamamelidae is to answer the question
which families should be included in this monophyletic group. By observing their pollen gr-
ains and stoma types of some representative species of Daphniphyllaceae, Hamamelidaceae and
Buxaceae under light microscope (LM) and scanning electron microscope (SEM,) and analy-
sing morphological, anatomical, palynological, embryological characters and chemical compone-
nts in the three taxa and Euphorbiaceae, we find that Daphniphyllaceae is very similar to Ha-
mamelidaceae, but greatly different from Euphorbiaceae, in inflorescence racemose or spicate,
calyx nearly reduced, stamens numerous and sometimes synandry, connective usually exserted,
disc absent, carpels 2; vessel with scalariform perforation plates and often not spiral-thickened,
fiber bordered-pitted; stomata mostly paracytic; pollen 3-colpate; tapetum glandular, endosperm
development cellular, obturator and caruncle absent; iridoid compounds present; sieve-element
plastids S-type.
The present authors have noticed the fact that Daphniphyllaceae is also similar to Mag-
noliaceae in the stamens numerous, anthers larger and filaments very short, connectives obvi-
ously exserted and with several bundles; anther wall thicker, endosperm development cellular, em-
bryo small. It is considered that not only are Daphniphyllaceae and Hamamelidaceae phene-
tically close to each other but also much possibly derived from a common ancestor, the extinct
group of Magnoliales. However, Daphniphyllaceae appears to be remote from Euphorbiaceae
and Buxaceae in relationship and should be separated from Euphorbiales and Buxales. Mean-
while, since Daphniphyllaceae differs from the members of Hamamelidales in the incompletely
septate ovary, drupaceous fruit, indistinct sexine sculpture of pollen grains, small embryo, and
an unique alkaloid, daphniphylline, but lacking proanthacyanins, the establishment of an order,
Daphniphyllales, for the family, is considered reasonable. According to our opinion, the
order is related to Hamamelidales rather than to Euphorbiales as originally suggested by Huru-
sawa (1954).