One Seeded Bur Cucumber (Sicyos angulatus)

This has been a summer for wild and wonderful weeds. Last month it was the tall blue lettuce. (Aline reports that the lettuce plant was measured at 16’.) This month we got a call from a homeowner above Maine Street who had an unusual vine that was overrunning a bed in his front yard. His initial thought was that it was a volunteer squash of some sort, but as the flowers and seeds formed he realized that what he had was clearly not a squash. After searching the internet for something similar with no results, he remembered a card that Aline had given him and called for help. As I was on my way to the bank the day he called, I stopped by to see his visitor.

Clearly the vine wasn’t a wild grape, a squash or a hop vine. Since there were flowers present it was possible to key it down using a Norton’s Wildflower Guide. The size of this thing made it almost impossible to believe it was the plant depicted in Norton’s, however it was verified when the homeowner opened one of the seed pods and discovered the presence of one seed. (Aha, One Seeded Bur Cucumber!) We then proceeded to confirm that there were male and female flowers present and that most of the other features matched the description. The leaves were a bit different from the picture in the wildflower guide but we attributed this to difference in age or population. The variations were minor. With an identification in hand we turned to the internet for further information.

Sicyos angulatus is a native annual “weed” that is a member of the Cucurbitaceae or gourd family. It closely resembles a cucumber vine but it can reach a length of 25’. The alternate leaves are 5-8 “ long with 3-5 lobes. They are slightly serrated and hairy on the bottom surface as are the stems. The vine climbs via branched tendrils at the base of some of the leaves. It sprawls when there is nothing on which it can climb.

The vine produces pistillate (female) and staminate (male) flowers.  Both male and female flowers are green. The male flowers have five petals with a central column of stamens that form a knob. The male flowers tend to form in small elongated clusters at the ends of long stems.  The female flower are single, have a single large ovary and form at the ends of shorter stem. When fertilized the female flowers develop a burred fruit that contains one seed. The fruit is green with long spines and fine white hairs. As it ripens it changes in color from green to brown. The plant flowers from July to September.

The burr cucumber reseeds itself readily and is considered a noxious weed in Indiana, Delaware and Kentucky. It is not listed as a noxious weed in Pennsylvania although it is becoming an increasing problem in no-till agriculture. It creeps into the fields from hedgerows and ditches where it tends to establish itself. The plant thrives in sunny wet locations.

The plant seems to have no use although the leaves are said to be edible, as is the seed. Care should be taken with the sap, as it may be irritating.