there is nothing in the morphology to suggest a relationship to the Coriariaceae (suggested by Chatin in 1856), Geraniales or the Sapindales (sensu Cronquist), though they allow that the, "level in evolution is about the same...." They also rejected any meaningful similarity between Limnanthaceae and Tropaeolaceae, as suggested by Dahlgren, who noted the shared possession of certain phytochemicals (glucosinolate, myrosinase, erucic acid and eicosenoic acid). They rejected this connection on the grounds that these phytochemicals also occur in the Brassicaceae which is assumed to be unrelated and suggest that the secondary compounds must be convergent. They concluded that the systematic position of Limnanthaceae is uncertain and cannot be presently determined. Dahlgren (1975), who believed strongly in the systematic value of secondary chemicals, placed Limnanthaceae in Capparales with Brassicaceae. He later (1980) placed Limnanthaceae together with Tropaeolaceae in the order Tropaeolales. Buchner, Halbritter, Prundner and Hesse (1990) investigated the pollen morphology of Limnanthaceae and discovered that the zonosulcate morphology is unlike the pollen of any known angiosperm and therefore relationships cannot be inferred from it. They reiterated Maheshwari and Johri's suggestion that a new order, the Limnanthales, should be created to contain the family. Rodman (1991a, b) included Limnanthaceae in a twin phenetic and cladistic analysis of all 15 taxa then known to produce glucosinolates. In UPGMA phenograms, Limnanthaceae clustered with Balsaminaceae. Similarly, cladistic analysis showed Limnanthaceae either in a clade with Balsaminaceae and sometimes Pentadiplandraceae or in a polytomy with Balsaminaceae, Pentadiplandraceae, Caricacaeae, Centrospermae, and a clade which includes all the rest of the glucosinolate taxa (except Drypetes). Rodman et al. (1993, 1997) assembled additional DNA sequence data sets for glucosinolate taxa and applied cladistic methods to generate hypotheses about relationship. They discovered that all the glucosinolate-producing taxa save Drypetes, form a clade. Despite the paucity of morphological synapomorphies (and therefore, to the surprise of many taxonomists), rbcL sequences have provided well supported evidence for the group's monophyly. 18S nuclear ribosomal DNA sequences have similarly, though less certainly, indicated a common ancestor for all the glucosinolate containing plants except Drypetes. The Angiosperm Phylogeny Group places Limnanthaceae in Brassicales, which is in the Malvid/Rosid II lineage. References Brassicales families