wide. Each fruit contains 2 or 4 seeds that are eaten by birds and can remain viable in the soil for decades. The stems climb by twisting around other plant stems in a counter-clockwise direction. Similar species Convolvulus arvensis can be confused with a number of similar weed species. Key traits are the small flowers often crowded together, and two sharp, backwards-pointed lobes at the base of the usually arrow-shaped leaf ending in a sharp apex. Juvenile stems exude a milky sap when broken. Calystegia sepium - Large white flowers. Squarish or rounded lobes at the base of the leaf. C. spithamaea - Leaf apex is rounded. Large white flowers. Only occurs in America. Fagopyrum tataricum - Annual. No milky sap. Fallopia convolvulus - Small greenish flowers. No milky sap. Ipomoea spp. - Ornamental species are summer annuals. More rounded, heart-shaped leaves in most species. In China, the most similar and only other vinaceous Convolvulus species is C. steppicola (most of the Convolvulus species are shrubs or herbaceous perennials), however this species has a thick woody rootstock, almost no petioles, and only grows in northern Yunnan, where C. arvensis is absent. Ecology Plants are typically found inhabiting farmland, waste places, along roads, in pastures, grassy slopes, and also along streams in North America. It is able to colonise hot asphalt surface by covering it from the sides of roads, and worm its way between pavement stones. It grows from 600 to 4500 metres in altitude in China, and is absent from the warmer southern provinces. It prefers dry areas with humus-poor, nutrient-rich and alkaline soils. It is a characteristic species in the phytosociological vegetation association Convolvulo-Agropyretum, belonging to the couch grass dry grasslands alliance (called Convolvulo-Agropyrion repentis in syntaxonomy). Like the other Convolvulus bindweeds of Eurasia, it is specifically pollinated by sweat bees in the genus Systropha. These are specialists (oligolectic) feeding upon the flowers of these plants, possessing unusual modifications of the scopa, such that almost the entire abdomen (including the dorsal surface) is used for carrying pollen, rather than the legs, as in most bees. Species of Systropha in central Europe (such as S. curvicornis and S. planidens, both uncommon bees) are essentially entirely dependent upon C. arvensis. Although both species specialise on the same plant species, S. curvicornis is a habitat generalist while S. planidens is only found in steppe habitats, although they are also found occurring