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VETCH
Vicia spp., family Leguminosae

The various species and cultivars of the genus vicia are grown for forage production, soil improvement, erosion control, and food for wildlife. The beans of some species are used as human food (Herman 1960, McKee 1948, McKee and Schoth 1934, Schoth and Hyslop 1925). Wheeler and Hill (1957*) listed 10 species, Gunn (1971) listed 11 species, and Heywood and Ball (1968) listed seven species, as being the more important ones; however, the pollination requirements of some of these species are unknown. The species on which there is pollination information include the following:

[gfx] fix small table:

Scientific name Common name V. angustifolia L. Narrowleaf vetch V. benghalensis L Purple vetch Scientific name Common name V. dasycarpa Ten. Woollypod vetch, or smooth vetch V pannonica Crantz Hungarian vetch V. sativa L. Common vetch, or spring vetch V villosa Roth Hairy vetch, woolly vetch, or winter vetch

Another important species ( V. faba L. ) is discussed under "Broad Beans and Field Beans."

The areas of production are primarily in the Pacific Northwest, Midwest, South, and Southwest. About a quarter of a million acres are devoted to vetch growing. The economic value is difficult to determine, but it doubtless runs into many millions of dollars.

Plant:

The vetches are generally partly-viny to weak-stemmed with leaves that usually terminate in tendrils and stems that are 2 to 5 feet or more in length, depending on the species and the condition under which they are grown. They are among the best of the legumes in their ability to be productive in low fertility or acid soils. They are often seeded with grain, the stalks of which support the vetch vines. The common vetches are annuals, except for hairy vetch, which may be either annual or biennial. All of the common agricultural species are viny.

Inflorescence:

The vetch inflorescence is usually a raceme that bears few to many solitary light-blue to dark-purple or lavender flowers. The flower, like that of most legumes, has the sexual column enclosed in the keel petal. If the column remains closed, only self-pollination can result (if the style and pollen are compatible). If the column is freed, or tripped, and the stigma comes in contact with pollen from other flowers, cross- pollination can occur. Some species benefit by tripping even if cross- pollination does not occur. Repeated visitation to the flower by pollinating insects also increases productiveness in some species. The flower must be tripped if bees are to collect pollen from it.

Nectar is usually secreted inside the corolla, sometimes on the outside of the base of the corolla. In many species, including at least V. sativa, angustifolia, and pannonica, nectar is also secreted in a nectary located on the leaf stipule (Knuth 1908*, p. 320; Herman 1960). Normally, when a bee visits the vetch flower for pollen or floral nectar, it settles on the wing petals, then forces its proboscis or "tongue" down the corolla. The pressure depresses the keel petal and forces the hairy style and pollen-laden anthers out. The pollen is thus shed onto the stigma, and some of it rubs off onto the bee, which then carries it to other flowers, resulting in cross-pollination. However, Weaver (1956b) stated that bees sometimes collect nectar from the side of the corolla without depressing the keel petal. Common and hairy vetches are an important source of excellent quality honey, and the production is usually sufficient for the storage of surplus quantities for the beekeeper. Hairy vetch is erratic, however, in its nectar production and attractiveness to pollinating insects (Alex et al. 1950). Common vetch produces a thick stipular nectar, which is more attractive to the bees than the floral nectar (Sculler 1956*).

Hungarian vetch has the reputation of supplying nectar in larger quantities for a longer period than any other cultivated plant (Schoth 1923).

Pollination Requirements:

Not too much is known about the pollination requirements of the different species and cultivars of Vicia. McKee and Pieters (1937) stated that "so far as is known the vetches are close-pollinated, and seldom if ever does crossing take place." However, there is no longer doubt that seed production of some species is greatly increased with bees. Alex et al. (1950), Bieberdorf (1952, 1954), Coe (1949), Mlyniec (1962), Mlyniec and Wojtowski (1962), Pritsch (1966), von Schelhorn (1942), Scullen (1956*), Thomas (1950), Weaver (1954, 1956a, b, 1957), and Wojtowski and Mlyniec (1964) have shown that production of hairy vetch (V. villosa) is greatly increased by bee visitation. Svetsugo and Kobayashi (1952) stated that fertilization of V. villosa is impossible when the plant is isolated from insects. Whether some of these workers considered the smooth- stemmed V. dasycarpa as a subspecies of V. villosa is not clear, but apparently the pollination requirements of the two are the same. Von Schelhorn (1946) concluded that Carniolian honey bees were superior to other bees in his area as pollinators of hairy vetch. Todd (1957*) listed both hairy and purple vetch in the group of plants that produced more seed as a result of insect pollination. He also stated that the brush arrangement of the vetch tripping mechanism, required repeated insect visits for thorough pollination. He listed common Hungarian and narrowleaf vetches as largely selfed plants. Scullen (1956*) stated that bees seldom visit Hungarian or the Willamette strain of common vetch, and that any pollination is probably done by bumble bees or other native bees. Scullen made no mention of the value of insect pollination or whether floral visitation might be increased with heavier bee populations than was used by beekeepers for honey production.

McKee and Schoth (1925) stated that common vetch is self- pollinated, however, Schoth (USDA 1942) later submitted the following list of vetches as benefited by insect pollination: V. villosa, V. benghalensis, V. pannonica, and V. sativa. In the revised (USDA 1946) edition, only V. villosa and V. pannonica were listed as benefited by bees.

Knuth (1908*, p. 325) stated that V. sativa anthers dehisce in the bud so that automatic self-pollination is inevitable. However, he noted that the flowers were visited by pollinating insects. Further, on the same page, he stated that the flower mechanism of V. angustifolia agrees with that of V. sativa, which would indicate that this species is capable of producing self-pollinated seeds. These flowers were visited by honey bees and other pollinating insects.

In summary, therefore, the data indicate that hairy vetch (V. villosa) is greatly benefited by insect pollination, and that this probably applies equally to woollypod (smooth) vetch (V. dasycarpa). Purple, common, Hungarian, and narrowleaf vetches may be benefited by insect visitation either in increased seed production during the current year or the ability to produce at the maximum potential in future years, although the literature is scant in this area.

The pollination requirement of all of the species of vetch grown in the United States is badly in need of clarification. Like many other of our agricultural crops and cultivars, the problem offers an excellent opportunity for plant scientists to conduct experiments likely to yield data of considerable economic importance to our agriculture.

Pollinators:

Honey bees are the primary pollinators of hairy and smooth vetch (fig. 192). This has been established quite positively by von Schelhorn (1946), Weaver (1956a, b, 1957, 1965), and others. There is little information on the floral visitors of other species. Scullen (1956*) stated that hairy vetch was worked freely by bumble bees and that they assisted in its pollination. He also stated that any pollination of Hungarian vetch was probably done by bumble bees or other native bees, but they seldom visit the flowers of the 'Willamette' cv. of common vetch. Where large- scale production of vetch seed is practiced in the United States, honey bees are used as a commercial practice. Alex et al. (1950) observed that fields with no colonies of bees within 2 miles produced 410 pounds seed per acre and fields with 0.1 to 1.0 colonies per acre within a mile produced 713 lb/acre; whereas fields with 1.5 to 3.0 colonies per acre within one-half mile produced 1,277 lb/acre. From these and other observations, they concluded that the bee saturation point had not been determined for hairy vetch.

[gfx] FIGURE 192. - Honey bee collecting nectar from vetch flowers.

Pollination Recommendations and Practices:

There are few recommendations on the pollination of vetch. Alex et al. (1951) conservatively concluded that more than one colony of honey bees per acre increases hairy vetch seed production. Weaver (1954) stated that several colonies per acre were necessary for maximum pollination of hairy vetch but that the use of more than one colony per acre "might not be economical." Later, Weaver (1956a) estimated that one strong colony could provide adequate pollination for 3 to 5 acres.

The data indicate that, because repeated visits to individual flowers are desired and because the vetches are not always overly attractive to bees, a relatively heavy bee population on the crop is desired. Thus, the several colonies per acre previously mentioned seems to be a more realistic recommendation than the one colony per several acres.

Of particular interest were the results of Drayner (1956), which showed that on continued inbreeding the ability to set selfed seed was progressively lost, but on hybridization self-fertility was restored. This is an area of benefit from pollination that has been largely overlooked and illustrates the value of bee pollination to such crops as vetches, which are considered to be self-fertile and even self-fertilizing. The results showed that the use of pollinating insects would be profitable and should be recommended for such self-fertile crops as the vetches.

LITERATURE CITED:

ALEX, A. H., THOMAS, F. L., and WARNE, B.
1950. IMPORTANCE OF BEES IN VETCH SEED PRODUCTION. Tex. Agr. Expt. Sta. Prog. Rpt. 1306, 3 pp.

THOMAS. F. L., and WARNE, B.
1951. BEES FOR VETCH POLLINATION IN TEXAS. In lowa State Apiarist Rpt. 1950, pp. 31-33.

BIEBERDORF, G. A.
1952. HONEY BEES AND VETCH P0LLINATION. Okla. Acad. Sci. Proc. 33: 36-37.

______ 1954. HONEY BEES AS VETCH POLLINATING AGENTS. Okla. Agr. Expt. Sta., Mimeo. Cir. M-250, 3 pp.

COE. L. E.
1949. POLLINATION OF HAIRY VETCH IN OKLAHOMA: THE NEARER THE BEES THE BETTER THE HARVEST. Amer. Bee Jour. 89: 558-559.

DRAYNER, J. M.
1956. REGULATION OF OUTBREEDING IN FIELD BEANS (VICIA FABA). Nature 177: 489-490.

GUNN, C. R.
1971. SEEDS OF NATIVE AND NATURALIZED VETCHES OF NORTH AMERICA. U.S. Dept. Agr., Agr. Handb. 392,42 pp.

HERMAN, F. J.
1960. VETCHES IN THE UNITED STATESÑNATIVE, NATURALIZED AND CULTIVATED. U.S. Dept. Agr., Agr. Handb. 168, 84 pp.

HEYWOOD, V. H. and BALL, P. W.
1968. LEGUMINOSAE. In Tutin, T. G., Heywood, V. H., Burges, N. A., and others, Flora Europaea, v. 2, pp. 80-136, Cambridge at the University Press.

MCKEE, R.
1948. THE LEGUMES OF MANY USES U.S. Dept. Agr. Yearbook l918: 701-726.

______and PIETERS, A. J.
1937. MISCELLANEOUS FORAGE AND COVER CROP LEGUMES. U.S. Dept. Agr. Yearbook 1937: 999-1031.

______and SCHOTH, H. A.
1925. COMMON VETCH AND ITS VARIETIES. U.S. Dept. Agr. Bul. 1289, 20 pp.

______and SCHOTH, H. A.
1934. VETCH CULTURE AND USES. U.S. Dept. Agr. Farmers' Bul. 1740, 22 pp.

MLYNIEC, W.
1962. [THE MECHANISM OF POLLINATION AND GENERATIVE REPRODUCTION IN VICIA VILLOSA ROTH.] Genet. Polon. 3: 285- [In Polish.] Abstract in Plant Breeding Abs. 34: 669, p. 76, 1964.

_____and WOJTOWSKI, F.
1962. [USE OF BUMBLE BEES FOR RESEARCH ON FLOWERING BIOLOGY OF HAIRY VETCH.] Ekol. Pol. Ser. B 8(1): 59-65. [In Polish, English summary.] AA-38/67.

PRITSCH, G.
1966. [INVESTIGATIONS ON THE SIGNIFICANCE OF HONEY BEES (APIS MELLIFERA L.) IN ASSURING SEED YIELD OF WINTER VETCHES (VICIA VILLOSA ROTH).] Arch. f. Geflugelz. u. Kleintierk. 15(3): 205-211. [In German, English summary.]

SCHELHORN, M. VON.
1942. [BIOLOGICAL STUDIES ON THE BLOSSOMS OF HAIRY VETCH.] Pflanzenbau 18(10): 311-320. [In German.]

______ 1946. [BIOLOGY OF FLOWERING AND SEED SETTING IN VICIA VILLOSA.] Zuchter 17/19: 22-24. [In German. ]

SCHOTH, H. A.
1923. HUNGARIAN VETCH IN OREGON. Oreg. Agr. Expt. Sta. Cir. 46, 4 pp.

______and HYSLOP, G. R.
1925. COMMON VETCH. Oreg. Agr. Expt. Sta. Bul. 213, 29 pp.

SVETSUGO, I., and KOBAYASHI, S.
1952. [STUDIES ON VICIA VILLOSA ROTH, WITH SPECIAL REFERENCE TO THE FERTILIZATION AND SEED PRODUCTION.] Crop Sci. Soc. Proc. 21(1/2): 150-151. [In Japanese, English summary.]

THOMAS, F. L.
1950. VETCH SEED GROWERS ASK FOR HONEY BEES. Amer. Bee Jour. 90: 315.

UNITED STATES DEPARTMENT OF AGRICULTURE.
1942. THE DEPENDENCE OF AGRICULTURE ON THE BEEKEEPING INDUSTRY . . A REVIEW. U.S. Dept. Agr. Burl Ent. and Plant Quar. E-584, 39 pp.

______ 1946. THE DEPENDENCE OF AGRICULTURE ON THE BEEKEEPING INDUSTRY . . . A REVIEW. U.S. Dept. Agr. Burl Ent. and Plant Quar. E-584, revised, 39 pp.

WEAVER, N.
1954. POLLINATION OF HAIRY VETCH BY HONEYBEES. Tex. Agr. Expt. Sta. Prog. Rpt. 1649, 5 pp.

______ 1956a. THE POLLINATION OF HAIRY VETCH BY HONEY BEES. Jour. Econ. Ent. 49: 666-671.

______ 1956b. THE FORAGING BEHAVIOR OF HONEYBEES ON HAIRY VETCH. I. FORAGING METHODS AND LEARNING TO FORAGE. Insectes Soc. 3: 538-549.

______ 1957. THE FORAGING BEHAVIOR OF HONEYBEES ON HAIRY VETCH. II. THE FORAGING AREA AND FORAGING SPEED. Insectes Soc. 4: 43-57.

______ 1965. THE FORAGING BEHAVIOR OF HONEYBEES ON HAIRY VETCH. III. DIFFERENCES IN THE VETCH. Insectes Soc. 12: 321-325.

WOJTOWSKI, F., and MLYNIEC, W.
1964. [BEHAVIOUR OF BEES DURING POLLINATION OF HAIRY VETCH.] Roczn. Wyz. Szk. Roln. Poznan. 19: 197-207. [In Polish, English and Russian summaries.] AA-245l67.

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