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378
william rosén
Thus my interpretation of the synergid-shaped endosperm cells
leads to the conclusion that the endosperm in Nolana, Solmviceae and
Scrophulariaceac may be derived from a common endosperm type most
probably similar to that of Verbascum.
This was a conclusion that does not well harmonize with the
current idea that a certain parallelism exists between the development of
external morphological and embryological characters. With regard to
the Solanaceae 1 quote Schnarf (17, p. 195): »Von besonderem Interesse
sind die Solanaceae, da sie eine ähnliche Mannigfaltigkeit in der
Endo-spermentwicklung aufweisen wie die Hydrophyllacea, indem nämlich
bier zellulares, nucleares und ausserdem ein intermediäres Endosperm
(Hyoscyamus) vorkommt. Dadurch dass es bei ihnen niemals zu einer
Ausgliederung von Haustorien kommt erscheinen sie ursprünglicher als
die Hydrophyllaceae und die Scrophulariaceae und Verwandte. Dafiir
dass die Solanaceae mit der zuletzt genannten Familien in engeren
Beziehungen stehen, können kaum aus der Embryologie Argumente
entnommen werden». However, it seems to me as if an unprogressive
phylogenetic development of external morphological characters often
may be compensated by a relatively rapid evolution of embryological
characters or vice versa, while in other cases a small transformation of
the external morphology may often be accompanied by such another
of the embryology and therefore my conclusion is better in accord with
Glisic’s idea (4, p. 43): »dass die einzelnen Merkmale sich oft in
ver-schiedene Richtung entwickeln können und class die
Entwicklungsrieh-tung der äusseren Form (als Resullante) oft keine Parallellität mil der
Entwicklungsrichtung der zu betrachtenden embryologischer Merkmale
aufzuweisen pflegt».
Now we will see if my interpretation of the endosperm should be of
any use for bringing order and system into the different endosperm
forms known in the Hydrophyllaceae. From svenssons work (18) we
know, that haustoria occur in the family. In Aemophila the cellular
endosperm (type 3 above) develops both micropvlar and chalazal
haustoria having only one nucleus. We are allowed to suppose that they
are reduced haustoria no doubt deriving from a multicellular type and
it is plausible to think, that it may originate from a Verbascum-type.
In Pliacelia viscida Svensson reports cellular endosperm, too, (type 3
above) and as to its chalazal cell he says (p. 38) that in later stages of
its development »entwickelt sich zu einem krsiftigen basalen
Haus-torium». A similar but smaller haustorium is reported in Pliacelia
diuaricata, and in Pliacelia congesta he reports endosperm of type 3
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