Sam J. Thomas Nature: Survey & Oxalis

Recently I spent a week pootling around the Aberystwyth district trialling my new protected environment weed survey and collecting samples of Oxalis section Corniculatae and Cardamine of the flexuosa group. After a number of false starts I'm now fairly happy with the survey protocol. It has become much more complex but it should allow me to:

Define the weed community of the protected environment
Relate the internal community to that of adjacent external communities
Differentiate niche communities such as pots and cracks
Describe the seasonal variation within these communities

My living collection of Oxalis and Cardamine is growing and I should soon have enough to begin my screening using molecular markers and cytological techniques. With any luck this will allow me to better define taxonomic units and slot them in to global studies and work being conducted by other botanists. Before all of this I thought I'd post a few of the most recognisable Oxalis taxa.

Firstly the deep purple Oxalis corniculata var. atropurpurea. This taxon is normally very distinctive due to its colouration though there seems to be some variation partly due to moisture and light.

Oxalis corniculata var. atropurpurea,
abandoned glasshouse,
Fron Goch University Farm,
SN 60602 82591, VC46

Second the smallest species: O. exilis. Less variable than other taxa, normally the most prostrate and often growing in tight mats its leaves are always a fresh bright green and its flowers are borne singly.

Oxalis exilis, abandoned glasshouse,
Fron Goch University Farm,
SN 60602 82591, VC46

Lastly possible Oxalis dillenii a much scarcer species. It was abundant in a single abandoned glasshouse at Llanbadarn. Obviously larger, more upright, its flowers are produced in small corymbs and its leaves have a slightly bluish tinge.