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While doveweed is a monocot, diamondflower is a dicot, thus a broadleaf weed, and a member of the Rubiaceae. The same family includes coffee as well as several other difficult turf weeds such as Florida buttonweed. Old World diamondflower was probably increasing in abundance on Florida golf courses during the late 1990s, although the plant was first pointed out to me in 1976 by the late Dr. Ev Burt, weed scientist at University of Florida - Fort Lauderdale. My first attempt to key out this weed landed me in the genus Oldenlandia, the same genus in which Linnaeus placed it when he described it in Species Plantarum in 1753. Since then, it has been transferred to the genus Hedyotis and its full handle is Hedyotis corymbosa. Asked to describe their fall problem weed, most golf superintendents remark on the small whitish flowers, and the tenacity of a short, patchy, ground-hugging weed. There may be a few other broadleaf weeds that come into play in the winter, such as the pigweeds, or Amaranthus, and even bur clover, but diamondflower is among the more important. The Rubiaceae, or coffee family, has several distinctive features, such as interpetiolar stipules. Looking at the point of attachment of the opposite leaves, there is a cup-like collar extending around the stem from one leaf to the other. This cup-like structure is the fused stipules of the opposite leaves.
Old World diamondflower forms weak adventitious roots along the stolon nodes, but it is primarily taprooted. This makes it relatively easy to pull up. In fact, the larger plants can be scooped up by hand or rolled into a small bale, then yanked up from the taproot. A single acre can have hundreds of individual plants of various sizes, which could make hand pulling time intensive. The seeds are relatively small, so that the plant can potentially repopulate an area. It is not known if this can occur during a single season. The phenoxy herbicides alone are not effective, but carfentrazone combinations, such as the new SpeedZone formulations, are moderately effective. Hedyotis
corymbosa is found in most counties in Florida It is also a weed in east Texas and is spreading in disturbed sites in western Australia. In Taiwan it is reported to have anti-inflammatory and liver-protective properties. It is used in Ayurvedic medicine. Chemical properties in Hedyotis have been shown to reduce tumors [Bad Link to CancerPrev.org, Abstracts of 1998 meeting, 22(101): Primary prevention (520).
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