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DescriptionThis native plant is an annual vine up to 25' long that develops multiple lanky stems. This vine can climb over adjacent vegetation and fences using its branched tendrils, otherwise it sprawls across the ground. The stems are light green, round or furrowed, and quite hairy. The alternate leaves are up to 8" long and across (excluding the petioles). They are orbicular-angular with 3-5 shallow lobes and their margins are slightly serrated. The upper surface of each leaf is relatively hairless, while the lower surface is finely pubescent, especially along the lower veins. The petiole of each leaf is up to 5" long; it is light green, rather stout, and quite hairy. The leaf blade is strongly indented at the base where it is connected to the petiole. Occasionally, branched tendrils and racemes of flowers occur oppositely from the alternate leaves along the vine. Bur Cucumber is usually monoecious and produces both staminate (male) and pistillate (female) flowers on the same plant. Each staminate flower has a green calyx with 5 teeth, a greenish white corolla with 5 spreading lobes, and a central column of stamens that is knobby at its apex. The teeth of the calyx are short and broad with recurved tips. The lobes of the corolla have a network of green lines on a white background. The staminate flowers are individually about 1/3" across and they tend to bloom in small clusters toward the apex of the raceme. Each pistillate flower has a large ovary that is enclosed within an ovoid fruit about ½" long. The surface of this fruit is covered with sharp spines and long white hairs; it is initially green, but later turns brown. A single style is exerted from the terminal end of this fruit. The pistillate flowers are bunched together in a short raceme; a typical raceme has 3-10 pistillate flowers. The peduncles and pedicels of both staminate and pistillate racemes are green and pubescent. The blooming period occurs from late summer to early fall and lasts about 3 weeks. There is no noticeable floral scent. Each bur-like fruit contains a single large seed that is brown and flattened; this seed is tapered at one end more than the other and it has a rough surface. The root system consists of a shallow branched taproot. This plant spreads by reseeding itself.