The results of this molecular analysis indicate that a number of morphological characters such as valvate capsule dehiscence, dark or light filaments and sessile stigmatic discs have arisen in parallel. The phylogenetic trees are incongruent with the existing taxonomy of Papaver, and a revised classification is suggested.

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The morphological similarities of most Taxus species (Yews) questions the correct identification of many samples of plant material. To determine if real differences exist, authenticated samples were collected from the same Arboretum, at the same time of year. Needles from six Taxus species and 25 varieties of a single species ( T. baccata ) were examined morphologically and chemically for paclitaxel content. The following ranges in results were obtained: needle length (7.7-22.4 mm); needle width (1.3-3 mm); needle area (11.2-48.4 mm 2 ); stomatal pore length (11.1-18.2 µm); stomatal number (82.3-128.9); paclitaxel content (0.002-0.025% of dry weight). Significant intra-specific differences were found to occur between the varieties of T. baccata , but no sufficiently distinctive inter-specific differences of taxonomic value were obvious between the species. Results questioned the identities ascribed to some samples. In general the results appeared to confirm the opinion that taxonomically Yews should be considered as a single species. Morphological comparison of Taxus with samples of the taxonomically related conifers, Cephalotaxus and Torreya , indicated significant microscopical differences in epidermal characteristics, stomatal arrangement, numbers and pore sizes.

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The concentrations of paclitaxel, 10-deacetylbaccatin III (10-DAB III), basic taxoids (= "total alkaloids", TA), taxine B and isotaxine B (= "taxines B", TBS) in the dried needles of 127 trees belonging to 30 Taxus cultivars and species were determined by HPLC. Neutral and basic taxoid contents varied in individual trees within species as well as among varieties and species. The objective of this large analysis was to select the highest-yielding trees for each metabolite.