The Beekeeper’s Companion Since 1861
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The Other Side of Beekeeping

Introduction to Genus Lupinus

- October 1, 2016 - George Ayers - (excerpt)

The Controversy Over Nectar Production

Historically there has been considerable controversy over the nectar production of lupines. This may at least be in part because some may produce nectar and others may not, or they may produce only very small amounts of nectar. It may also result from variations in observational technique used to provide an answer to the question. Below I provide a review of this question. The reader needs to be forewarned not to expect a final definitive answer. The first three references deal with a common topic, the structure of the staminal column, each reference adding a potential bit on insight into the question of nectar production. Beyond that, the remainder of the references are provided in the chronological order that they appear in the literature.

1926: John Lovell[9] seems to offer a way of distinguishing nectar-producing Lupinus species versus those that produce only pollen. He claims that in the nectariferous species, nine of the ten stamens of the flowers are united to form a tube, but that the tenth stamen remains free, allowing a bee to insert her tongue into the nearly closed-off tube by inserting it into the otherwise sealed tube on either side of the free stamen. In the species where all ten stamens are joined together they produce a closed cylinder and the bee cannot insert her tongue to obtain the nectar of the flower. Interestingly, while this seems such a reasonable explanation of at least some of the variation in the production of nectar by lupines, in the beekeeping literature, I found it mentioned only by Harvey Lovell[8] and Lawrence Goltz[5] in their honey production booklets (see below). The keys of Martin Wojciechowski[20] seem to indicate that John Lovell was correct about the variation in staminal structure and that it might therefore provide a partial answer to why there seems to be so much variation in the literature concerning lupine honey production. The Wojciechowski keys (group 3) found in the Jepson Manual (second edition) seem to indicate that at least in California, with the words “filaments of all stamens fused” (page 721) that in California all the native lupines have all of their ten stamens fused. If both this statement and John Lovell’s statements are correct, none of the California lupines should produce nectar. I have no verification of this, however.

1966: Harvey Lovell[8] adopts his father’s view and adds to it that in the case where all the stamens are joined together there are also no nectaries.

1977: The Lawrence Goltz[5] version of the Harvey Lovell publication repeats Lovell’s suppositions that some lupines have a closed staminal tubes and in these cases, there are also no nectaries. Primarily referring to the Texas blue bonnet (Lupinus subcarnosus) he seems to agree with the closed stamenal tube and no nectaries story. He goes on to say that while the distribution of Lupinus is general, they seem to be most common in Texas and surrounding states where bees collect pollen, but are rarely reported as collecting nectar. He then adds “In Oregon bees have been seen collecting nectar from L. nanus, L. albicaulis and L. laxiflorus (which) have (also1) been reported as pollen plants.” This seems to disagree with Burgett, Stringer and Johnson[2] who state “Bees are known to use L. bicolor as a nectar source and L. laxiflorus as (a) pollen source.”

1908: Sanborn and Scholl[16] writing about L. subcarnosus (one of the Texas bluebonnets) as a Texas bee forage state “honey yield good; also pollen of very bright and orange colors.”

1911: Richter[14] in one location places Lupinus affenis in the category honey plants not known to yield a surplus (presumably nectar) and in another section tells where in California the species grows, that it blooms January to April but seemingly contradicts the information in the first section, stating that there is “honey from the flowers.”

1921: Coleman[3]: In his pieced-together set of articles concerning California honey plants and writing apparently about L. albifrons says, “As a general thing, the Lupines are nectar producers, but on account of the deep flowers are only visited by bumblebees.” In this case (presumably L . albifrons) and also a few other species, the flowers are small and, therefore, the nectar is available to honey bees.

1939: Oertel[11] from his extensive set of questionnaires reports the genus Lupinus and three species of Lupinus as having some importance in six states. There was no indication concerning whether the importance resulted from nectar and/or pollen production.

1941: Vansell and Eckert[19] indicate that apparently most of the lupines are not very attractive to bees. They indicate that while lupines are sometimes credited with a crop of honey, there is some doubt concerning …