by Alan M. Kapuler Ph.D. and Kusra Kapuler
Comment by AMK as of 1-16-2005: new aspects of relationships among living organisms are now continually being revealed by the 'omic' sciences. The following paper written several years ago combined molecular biology with kinship gardening. In the interrum, the APG (Angiosperm Phylogeny Group) has updated their work (2003) and I will update the biodiversity based kinship gardening layout for the world flora in the near future.
In 1998, in a series of articles published in the the Annals of the Missouri Botanical Garden, the Angiosperm Phylogeny Group, a brilliant assemblage of botanically inclined folks, presented what is the first major revision of the tree of life of all the flowering plants that grow on earth since its presentation by Linneaus in the mid 1700's(1).The systematics of flowering plants as established by Linneaus and practiced by legions of biologists during the last 3 centuries has been based on external, morphological characteristics emphasizing the reproductive system. Up to now, the flowers have determined the way we see natural order among the diversity of a third of a million species. Given the size of the DNA of plants, 25,000 genes for Arabidopsis, for example, perhaps 3-5% determine the flowers. So our phylogeny for the plants has been based on only a small part of the total genetic aspect of the plants. Hence closely related plants that are very different in appearance would be misplaced in previous structure-based systems.
Deciphering the genes is a major revelation of our times. We are unraveling the mystery of the tree of life in all its fineness and extraordinary detail, accurate to sequences and patterns of DNA bases that are being compared organism to organism to give totally new understandings about how life is as it is. This molecular insight is generating a new look into the tree of life of the flowering plants.
Several genes in plants, some in the chloroplastids, relic symbiotic bacteria that live inside plant cells, others in the nuclei of the cell themselves, have been examined and compared for a wide and deep variety of flowering plants. Following rules of the science of cladistics, the branching patterns of inheritance that have recorded thru countable and large numbers of generations, the way genes and traits give rise to leaves, flowers, pollen, food and fertility, a new pattern has been discerned in many of the relationships. Our previous working model for the world flora was the fruit of the Classic Era in Plant Taxonomy. From Linneaus and Hooker to Dahlgren and Thorne, from Engler, Prantl and Reichenbach to Willis and Liberty Hyde and Zoe Bailey, from Bessey and Gray to Cronquist and Takhtajan, the morphological view developed its outlook and we have used it as a basis for planting kinship gardens. Now a new era arises, based on the molecular information that is part of the emerging science of genomics. By examining the new system in context of the old, we see that a large part of the older system was accurate and that the preeminant botanists of the past several hundred years did a remarkable work in fitting together the puzzle of diversity.
However, several important aspects of the world flora were not understood. "Maybe it was the roses". Indeed the relationship among major groups including the myrtles, the roses, the cotton alliance, the citrus alliance, the ericas and several other large alliances has been reassessed, rearranged and become easier to understand.
The process of integrating the mosaic of more than 300,000 plant species has already taken more than 250 years. We are working towards a system of relationships among the major groups of plants that allows for kinship gardens that maximize diversity in all gaian ecosystems.
The first diagram is a simplified version of the major groups of flowering plants as presented by the Angiosperm Phylogeny Group. The angiosperms found well represented in the fossil record both as plants and pollen we call 'The Old Ones' and includes the Magnoliales, the Piperales, the Proteales and the Laurales. From these branch the Monocots. Then follow the Eudicots, the Core Eudicots, and the Asterid and Rosid clades.
The major changes that take place in going from the classical morphological taxonomy of Linneaus to the molecular taxonomy of the Angiosperm Phylogeny Group thus far are the following:APG Monocots:
1. The largest group of plants, the orchids (Orchidales) become part of the Asparagales, making it the largest plant order. Although it is not explicitly clear how the orchids branch from the hyacinths, alliums and terrestrial probably temperate zone saprophytes of Laurasian supercontinent, what has been learned is that the irises too are shifted from the lily order (Liliales) to the Asparagales and that the connection between the orchids and the irises needs further clarification. For the Asparagales and Liliales, we have used the descriptive term 'Asparagoids' to parallel the 'Commelinoids' used by the the APG for the alliance of the Poales, Zingiberales, Bromeliales and Arecales. It seems likely that further work will support moving the Bromeliales from the Commelinoids to the Asparagoids together with the Vellozias.2. The aroids (Araceae) are now part of the Alismatales, the Water Plantain Order.3. The Yam Order (Dioscoreales) now includes the Burmanniaceae and becomes an order distinct from the Lily Superorder.4. The Palms (Arecaceae) and the Banana Order (Zingiberales) become orders in a new supergroup, the Commelinoids, which also includes the Poales and Commelinales. The Cattails (Typhaceae) are now included in the Grass Alliance (Poales).5. The Pandanales is separated from the Arecales and gains the Velloziaceae which is moved from the Bromeliads. The Bromeliaceae is its own family as yet unassigned to an order.6. The Liliales which have lost the Iridaceae has gained the Smilacaceae, Philesiaceae, Luzuriagaceae and Ripogonaceae.7. The Acorales becomes a new order of 2 species in a single genus, Acorus.
APG Dicots:There are many significant changes in the dicots and we only highlight some of the most striking and directly useful to gardeners.1. 'The Old Ones' now include the Proteales such that these Australians and South African plants are included in the longterm stable gene pool of Gaian ecosystems.2. The Core Eudicots is an enlarged Caryophyllales, now including several disparate groups including the Santalales (mistletoes), the Vitaceae (grapes) and the Saxifragales, split off from the Rosales and bringing the Crassulaceae closer to the succulents of the Mesembryanthemaceae (iceplants), Basellaceae and Portulacaceae. Buckwheats and Limoniums (statice) are also in this group.3. The Asterids, Euasterids 1 and 2 make up the Asterid Clade. Asterids have seen an expansion of the Ericales to include many groups previously dispersed in other orders while retaining the Cornales.Hydrangeas are split from the Dipsacales now in Euasterids 2.4. Eurosids 1 becomes a major group is this new layout. The Citrus Superorder (Rutanae) has been redistributed. So has the Violanae. Their members have been relocated primarily in the Eurosids 1 and 2. Also brought together in Eurosids 1 are the Fabales, increased with the Polygalaceae which has papilionaceous flowers like the Fabaceae, and the Rosales which have gained the Urticales, moved from the Cotton Alliance (Malvanae). The Eurosids 2 has 4 Orders. One is the Malvales and includes the Bombacaceae, Tiliaceae and the Sterculiaceae as well as the Malvaceae. The other three are the Myrtales, the Brassicales and the Sapindales. The inclusion of the Myrtales in the Eurosids 1 is very different from previous taxonomies and makes sense of some of the kin traits held by members of the Fabales and the Myrtales.5. Eurosids 1 has most of the temperate fruits. Eurosids 2 has most of the tropical fruits. There is a large temperate zone node between Eurosids 1 and Eurosids 2 which includes part of the legumes, the brassicas, the beeches, birches, roses and related taxa. That the new layout makes sense of ecological and environmental aspects of the plants does much to recommend it. Cladistic analyses of plant phylogenetic relationships based on molecular data will continue to emerge from the increasing amount of genomic research done with many groups. Discoveries of new genera and species of plants also continue at a steady pace such that during the past 9 years more than 21,000 new species have been described(2).
This is a new working model of the flowering plants. Finer details can be found at family and tribal levels. These levels will be presented in subsequent Peace Seeds Resource Journals. Meanwhile we encourage you to explore the new layout, compare it with the one generated from flower morphology taxonomy and to investigate the construction of kinship gardens based on these insights.
Conclusion: These new kinship layouts can be used to plant conservation gardens that maximize diversity. The new phylogeny of the flowering plants (APG system) is both very different and very similar to the phylogeny generated by the flowers. It improves our understanding of relationships that heretofore have been obscure. We expect that further molecular cladistic analyses will continue to improve our understanding of the plant tree of life and to provide an increasingly better working model for the world flora.
1. Angiosperm Phylogeny Group 1998 An Ordinal Classification for the Families of Flowering Plants, Ann. of the Missouri Bot. Gard. 85:531-553.2. Prance, G.T., H. Beentje, J. Dransfield and R. Johns 2000 The Tropical Flora Remains Undercollected, Ann. Missouri Bot. Gard. 87:67-71.