Interactive key to the genera of Euphorbiaceae s.l., Salicaceae & Achariaceae

This project will develop a single online interactive key to the genera of Euphorbiaceae, Centroplacaceae, Pandaceae, Peraceae, Phyllanthaceae, Picrodendraceae, Putranjivaceae, Salicaceae, Achariaceae and Gerrardinaceae. The group is large (c. 400 genera) and widespread. Identification of genera is difficult both within and between families.

Glochidion kerangae (Phyllanthaceae) Photo: Gill Challen

This project will develop a single online interactive key to the genera of Euphorbiaceae, Centroplacaceae, Pandaceae, Peraceae, Phyllanthaceae, Picrodendraceae, Putranjivaceae, Salicaceae, Achariaceae and Gerrardinaceae. The group is large (about 400 genera) and widespread. Identification of genera is difficult both within and between families.

The families treated fall into two groups. The first includes Euphorbiaceae, one of the largest and most widespread of the eudicot families (220 genera, 5700 species), and a number of families only recently separated from it, i.e. Centroplacaceae, Pandaceae, Peraceae, Phyllanthaceae, Picrodendraceae and Putranjivaceae. The group is well represented in many vegetation types, but presents difficulties in identification. The families are distinguished largely on the basis of molecular evidence and/or morphological characters that are difficult to use (e.g. ovule number per ovary locule). The flowers are often very small (sometimes just 1 – 2 mm diameter), and reduced in form. Important economic taxa include Manihot esculenta (cassava) and natural rubber (Hevea brasiliensis), both Euphorbiaceae.

So far the second group largely comprises Salicaceae and Achariaceae. Both families have undergone dramatic changes (Chase et al 2002) and now contain many tropical genera previously housed in Flacourtiaceae. Some of these are often confused with Euphorbiaceae and its allies, for example Flacourtia, Xylosma (both Salicaceae), Lindackeria and Poggea (both Achariaceae).

Original datasets were drawn from literature (e.g. Radcliffe-Smith 2001) and direct observation of herbarium collections at K and early versions of the Key used DELTA software.

For 2010 -11 effort has focused on translating the Key to Lucid3 software, importing provenance coding for Euphorbiaceae and allies and, for neotropical and subtropical Euphorbiaceae and allies, checking the original dataset (direct observation of herbarium collections at K plus collaboration with external specialists) and adding rich image galleries of scanned / photographed herbarium material. Provenance coding speeds up identification by directing the user to a subset of genera tailored to their country of interest. The codes were imported from the World Checklists, with in-house IT support. The image galleries are an invaluable rapid identification tool, in many cases bypassing the requirement for specialist knowledge of floral morphology. All images of herbarium material were produced in-house; high resolution copies of full sheet scans will be added to the Herbarium Catalogue. The Iinteractive Key links through to taxon pages and further image galleries on the Malpighiales Scratchpad.The 2010 - 11 work, including a fresh external perspective to the project, is credited largely to Emma McLarnon (BSc Biology Leeds University 2008 - 12, work placement at Kew 2010 - 2011).
 

The Key is hosted by Lucidcentral, home of the Lucid family of software, and can be visited via the Malpighiales Scratchpad.