| Papaveraceae s.l., contains 40 genera and more than 800 species in the world, most of which are herbs and mainly distributed in north temperate zone. China has 19 genera and 443 species which occur in the northern and southern parts, especially concentrating in the southwest part of China. There has been much debate on the classification of this taxon both within and below the family owing to lacking sound morphological evidence as well as covering the large number of species. For example, Corydalis, the largest gunus in Papaveraceae s.l. whose morphology varies a lot, contributing to an obvious and reticulate evolution, is very difficult to classify according to phylogeny. Since 1950s, micro-morphological characteristics of seeds have been widely used in classification and systematics of angiosperms. Such practice has shown that micro- morphological structure of seeds is of great importance in taxonomy whether at the level of families, genera, or species. Therefore, we study the poppy plants in terms of micro-morphological characteristics of seeds, to explore the phylogenetic relationship and systematic position of inter-genera and intra-genera in the family.According to Wu Zheng-Yi (1996,1999) system, the micro-morphological characteristics of seeds from 17genera,113 species and 1 subspecies of Papaveraceae s.l. (including 29 setction,81 species 1 subspecies of Corydalis) were observed by using scanning electron microscope, in order to provide new evidence for the classification of the family. The main results are as follows:1. There are many seeds morphology types, including (nearly)square, (nearly)circular, broadly ovate, (nearly)spherical, elliptic, nephroid, obavate, triangular, broadly obtrullate. Seeds of some genera have genus-specific, such as nephroid in Papaver, triangular in Glaucium and broadly obtrullate in Hypecoum. The colour of seeds is mostly black and brown, and most seeds are shiny. The seeds size is quite different among different genera. The largest is E. chionantha Hance in Eomecon and the average size is 3.11×2.18mm, the smallest is P. somniferum L. in Papaver and the average is 0.69×0.38mm. The size of other species is varing from minimum and maximum above in this family.2. The seed-coat surface ornamentation is diverse and has 16 types. These are reticulate type, rough reticulate type, coral-like rugose type, rugose type, negative reticulate type, irregular protuberance-reticulate, rectangular protuberance-reticulate, spinulose-verrucate type, stripe type, striate type, spinulose-reticulate type, clavate protuberance-reticulate, verrucate protuberance-reticulate type, head-like protuberance type, granular-reticulate type, rounded protuberance-crack-reticulate type and bubble-like protuberance type. Among them, there are 8 types in Corydalis and the following 6 types are peculiar, such as spinulose-reticulate type, granular-reticulate type, verrucate protuberance-reticulate, head-like protuberance type, granular-reticulate type and rounded protuberance-crack-reticulate type. In the 18 genera of Papaveraceae s.l., the seed micro-morphology of A. mexicana L. in Argemone, Meconopsis, P. somniferum L. in Papaver, Eschscholtzia and Dactylicapnos were reported before. The seed micro-morphology of other genera and species are reported for the first time in this article. At the same time, the seed-coat surface ornamentation such as rough reticulate type, rugose type, reticulate type and stripe type were reported before, and other types are first reported.3. Hypecoum has unique seed-coat surface ornamentation and unique seed shape of broadly obtrullate, the results support its dependence as a separate family Hypecoaceae and also confirm the monophyly of Hypecoaceae.4. Glaucium and Dicranostigma are both rough, reticulate type and both monophyly, indicating that the results of seed-coat surface ornamentation support the view of their belonging to Papaveroideae.5. In view of the seed-coat surface ornamentation, Fumariaceae, Papaveraceae s.str., and Papaveroideae have several types, thus supporting their polyphyly while Eschscholzioideae only has one type which is rough reticulate, supporting its monophyly.6. Micro-morphology of the seed-coat can provide some valuable evidence for relationship among some genera and has some taxonomic significance at the level of genera. It can provide evidence for the identification of species and has some taxonomic significance at the level of species below genera and section. 7. Some species such as Corydalis edulis and C. pallida have different seed-coat surface ornamentation types and variation occurs within species. These may be due to their different geographic distribution. |
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