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ZIGZAG CLOVER⁵⁶
Trifolium medium L., family Leguminosae

Zigzag clover is of little or no economic importance in the United States. Wheeler and Hill (1957*) stated that if seed were available it might become one of our good pasture legumes for our moist cool climates. It grows primarily as an escape plant in infertile soil or waste places in northeastern United States.
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55 See "Clovers, General."

Plant:

Zigzag clover is a stout perennial up to 18 inches tall with stems that grow in zigzag fashion, hence the mane. It spreads by seeds and by rhizomes on underground stems.

Inflorescence:

The flower head and flower mechanism are similar to red clover, but the flowers are of a brighter, deep red-purple. Nectar secretion is about the same as in red clover (Robertson and Armstrong 1964). The heads average about 37 florets and set 14 to 21 seeds per head if properly pollinated. The floret has two ovules but produces only one seed.

Pollination Requirements:

Robertson and Armstrong (1964) believed that the long corolla tube precluded pollination by honey bees, but that bumble bees were most important, with seed setting directly proportional to the frequency of bumble bee visits. Townsend (1967) made detailed studies in Colorado on the self- and cross-incompatibility of this crop. He bagged heads to exclude pollinators and found that of 42 noninbred bagged plants tested all were highly self-incompatible, 36 did not set a single seed under selfing, and the seed set for the remaining six ranged from only 0.25 to 1.25 seeds per head versus 14 to 21 in open-pollinated heads. He believed that the poor seed production of zigzag clover may be due to preference of pollinators for other plants. Keim (1957) compared production of plants caged with honey bees with open plots near honey bee colonies and concluded that differences in seed set of various clones were due to genetic differences and to bee preference.

Pollinators:

Knuth (1908*, p. 293) reported that honey bees as well as Andrena, Bombus, Colletes, Halictus, Megachile, and Psithyrus bees, visited the flowers. Robertson and Armstrong (1964) recorded 97 percent bumble bee, 2 percent honey bee, and 1 percent other bee visitors. Keim (1957) considered honey bees quite important.

Pollination Recommendations and Practices:

None.

LITERATURE CITED:

KEIM, W. F.
1957. SEED SET FAILURES IN ZIGZAG CLOVER. Agron. Abs., p. 74.

ROBERTSON, R. W. and ARMSTRONG, J. M.
1964. FACTORS AFFECTING SEED PRODUCTION IN TRIFOLIUM MEDIUM. Canad. Jour. Plant Sci. 44: 337-343.

TOWNSEND, C. E.
1967. SELF- AND CROSS-INCOMPATIBILITY AND GENERAL SEED SETTING STUDIES WITH ZIGZAG CLOVER. Crop Sci. 7: 76.

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