Cystoliths and raphids occur in a restricted number of families and often ate of diagnostic value. Cystoliths are outgrowths of the cellulose wall impregnated with calcium carbonate and occur in the epidermal or ground parenchyma cells. They are found in about fifteen dicotyledonous families, particularly in Acanthaceae, Cannabaceae, Moraceae and Urticaceae. Raphids are elongated calcium oxalate crystals aggregated into bundles and often occurring in exceptionally large cells which at maturity are dead and filled with mucilage. They occur in about 54 dicotyledonous and a number of monocotyledonous families (Metcalfe, 1963; Metcalfe & Chalk, 1950; Tomlinson, 1961). The descriptive terminology employed by taxonomists to indicate the presence of these cell-inclusions has not always been consistent. For example, both these terms 'cystolith' and 'raphid(e)' have been used by different authors to indicate the presence of cystoliths in the leaves of some members of Acanthaceae (Bremekamp, 1948; Gamble, 1924; Leonard, 1951-1958 and Santapau, 1951). While Bremekamp and Leonard consistently used the term 'cystolith', Gamble and Santapau preferred the term 'raphide', and Wight (1850 & 1853) described the cystolith-bearing leaves of Elatostema (Urticaceae) and Rostellularia (Acanthaceae) as 'lineolate'. The presence of cystoliths and raphids cannot be easily detected in most fresh materials. When specimens are dried, these inclusions appear as white elevations and sometimes even give a chalky-white appearance to the leaves, as in the raphid-bearing leaves of Gisekia (fig. 3). Examination with a simple hand-lens is sufficient to reveal the ditinct pattern in their distribution. However, such a superficial examination is not sufficient to determine the nature of these inclusions, i.e., whether they are 'cystoliths' or 'raphids' (compare figs. 1 & 2 with 3 the first two show cystoliths and the third raphids). Only microscopic examination of cleared materials or sections will reveal their true nature. It is not always possible to subject all herbarium materials to microscopic study, and the herbarium taxonomist is likely to make mistakes in employing the terms 'cystolith' and 'raphid', which are better used in anatomical descriptions. Hence the term 'furuncle' (Lat. swelling; adj. 'furunculate') is proposed for use in describing plant organs having 'cystoliths' or 'raphids' as cellinclusions, discernible in herbarium specimens at low magnifications as distinctly elevated areas on the surfaces of leaves and other organs. Materials shown in the plate may be described as (fig. 1) leaves adaxially furunculate, furuncles dense, irregular; (fig. 2) leaves adaxially furunculate, furuncles boomerang-shaped and oriented at right angles to the midrib; and (fig. 3) leaves furunculate, furuncles few above, crowded and appearing chalky-white below.