Portulaca species: Portulacca

Family

Portulacaceae

Common Names

Portulacca, moss rose, rock moss, sun plant - Portulaca grandiflora

Purslane - P. oleraceae

Plant Description

Comprising a genus of 100 semi-succulent, erect or prostrate, mostly perennials, Portulaca are native to warm drier regions of the world. Leaves are alternate or opposite, fleshy, round to flattened, the upper few leaves forming an involucre surrounding the showy flowers, with 4 - 6 petals and prominent multiple stamens. Flowers have a wide range of colors ranging through white, yellow, pink, purple, or red and variously striped (Fig. 327).

Figure 327. Portulaca species.

Toxic Principle and Mechanism of Action

Oxalates are the primary toxins in Portulaca. The common garden weed purslane (P. oleraceae) may have oxalate levels as high as 17% dry matter [1]. Purslane has been used as a food source as long as it is well cooked to remove the soluble oxalates. Animals have been poisoned by eating large quantities of the plant and developed typical signs of oxalate poisoning seen with other oxalate containing plants such as wood sorrel (Oxalis spp.) [1]. If eaten in quantity the oxalates can induce hypocalcemia and oxalate nephrosis.

Risk Assessment

Portulaca are commonly grown as summer time drought tolerant plants in many gardens. The common weed purslane (Portulaca oleraceae) is frequently removed in large quantities from gardens and may be disposed of in animal enclosures where it may be readily consumed by livestock. In quantity, the plants can cause fatal poisoning.

Clinical Signs

Sheep that have eaten large amounts of the plant become depressed, ataxic, and recumbent because of hypocalcemia following the formation of insoluble calcium oxalate. Oxalate crystals may be seen in the urine and animals die from an oxalate nephrosis.

In the event oxalate poisoning is confirmed, the intravenous administration of calcium borogluconate may rapidly reverse hypocalcemic effects, but oxalate nephrosis may not be affected and animals may die several days later from renal failure.