The present research project has an objective to investigate the evolutionary-ecological divergence of the so-called Arcto-Tertiary elements which exhibit typical disjunct distributions between the temperate zones of eastern Asia and eastern or western North America. In this three years project, the main emphasis has been placed to investigate on the following points :
(1) geographical and ecological distributions of various Arcto-Tertiary elements ; (2) life history and demographic characteristics of various herbaceous elements ; (3) karyological characteristics (types of resting nuclei, chromosome numbers and karyotypes) ; (4) molecular characteristics (RFLP patterns of cpDNA ; structures of rbeL gene, etc.), and evaluations of life history and molecular data in terms of evolutionary-ecological implications.
Results : 1. Living materials collected during three years were as follows : Monocots : (1) Trillium, (2) Disporum (Prosartes), (3) Clintonia, (4) Smilacina, (5) Polygonatum, (6) U
vularia, (7) Helonias(8) Chamaelirium, (9) Erythronium, (10) Medeola, (11) Scoliopus, (12) Allium, (13) Lilium, (14) Zygadenus, (15) Pritillaria, (16) Calochortus, (17) Tofieldia, (18) Streptopus, (19) Lysichtum, (20) Arisaema, (21) Brachyelytrum, (22) Amarylidaceae ; Dicots : (1) Panax, (2) Asaruin, (3) Achlys, (4) Caulophyllum, (5) Vancouveria, (6) Kdenocaulon, (7) Epigaea, (8) Dicentra, (9) Hydrophyllum., (10) Mitchella, (11) Hepatica, (12) Podophyllum, (13) Cimicifuga, (14) Coptis, (15) Oxhlis, (16) totaenia, (17) Claytonia, (18) Mitella, (19) Boykinia, (20) Phryma, (21) Trauttvetteria, (22) Viola, (23) Impatiens, (24) Tovara, (25) Polygonum, (26) Rumex, (27) Chrolanthus, (28) Achilles, (29) Aster, (30) Cacalia, (31)Heuchrea, (32) Prenathes. The total numbers of genera and species attained 54 genera and 135 species of the Arcto-Tertiary elements. 2. Herbarium specimens collected attained ca. 1, 500 sheets which are at present under investigation ; especially most of the cool-temperate and warmtemperate ferns, attaining 34 genera and 119 species, were collected, which would be the first extensive collections of North American ferns. 3. Chromosome numbers and karyotypes of all five North American Disporum subgenus Prosartes were determined. All other liliaceous materials collected are being studied at present. 4. Life history and demographic characteristics of 30 North American Trillium were critically investigated. Two Scoliopus species and Medeola virginiana were/are also studied (both Trilliaceae). 5. CpDNA characteristics, as revealed by RFLP analysis and sequencing of rbcL gene have been examined on various Arcto-Tertiary elements, with a main emphasis on the Liliaceae s. lat. and Araceae, and based on these new evidence their phylogenetic relationships were analyzed. The groups studied wre : Trillium, Medeola, Scoliopus, Disporum (Prosartes), Maianthemum, Clintonia, Streptopus, Smilacina, Uvularia, Helonias, Heloniopsis, Narthecium, Metanarthecium, Chamaelirium, Chionographis, several Araceas genera. 6. Life history characteristics of Erythronium oregonum, E. elegans, E. howellii, Uvularia grandiflora, U. sessifolia, U. perfoliata, and U. pudica were/are now under investigation. Reproductive biology and life history features of Arisaemea triphyllum, caudatum, and A. canadense are being critically studied.
Papers compiling all the results obtained and further critically analyzed on the above mentioned groups are now in preparation or have already been published or submitted to relevant scientific journals, respectively, as shown in a list of publications.
Patterns of leaf development, leaf allometry, and geographical variations of several fern species, e. g., Strupthioptteris, Blechnum, Polystichum, Dryopteris, etc. were also critically examined based on the materials collected in the present projects as to the results are now in preparation.