Note on the early development of the integument in some Juglandaceae together with some general questions on the structure of Angiosperm ovules

Recently a review on the Angiosperm ovule has been published by the well-known Indian botanist V. Puri (1970). In this review the author stressed the differences between Angiospermous and Gymnospermous ovules, and he refused to accept their comparability or common descent. In this respect Puri comes close to Eames (1961). Both authors tend to regard the ovules as complex emergences. Apart from the main theme, there is a striking passage in this review dealing with the Hugo de Vries Laboratory at Amsterdam. According to Puri in that laboratory facts are sacrificed for hypotheses (p. 10). In the following we would like to start with the facts concerned and present them in a more convincing way, and then ask some simple questions on the structure of the ovules in order to show just how little precise information is available. This lack of information has had the effect of producing many different hypotheses. Boesewinkel and Bouman (1967) reinvestigated the initiation of the single integument in some Juglandaceous ovules. In a histogenetic study they showed that the development starts with subdermal and is followed by dermal periclinal divisions. They also stated that the integument arises as two halves, or valves, which are free above but become fused below especially in later stages. Unfortunately, however, they failed to give an unequivocal demonstration of this paired development by means of some good photographs. It was this lack of proof that led Puri to reject the evidence. However, it should be reported that earlier Shuhart (1932) and Leroy (1954) had published the paired initiation of the integument lobes (in Carya spec. and Platycarya strobilacea resp.), and had given photographs of microscopic slides showing cross-sections of the distal part of the nucellus flanked by two opposite tips of the young single integument. In the present paper we present two similar photographs, one of Pterocarya fraxinifolia, the other of Engelhardia spicata. In addition two other ‘true to nature’ photographs are given, showing two developing ovules of Pterocarya fraxinifolia, as they can be observed directly under a stereo dissecting microscope at low magnification, after the young pistil wall is carefully removed. There is no escape from the fact that the integument in these plants grows like two fusing lobes. The hypotheses are a different matter.