The Other Side of Beekeeping

 December 2014

 The Other Side of Beekeeping

Family Fagaceae - Beech (and Oak) Family

(excerpt)
 
 

The Fagaceae is an important plant family generally considered to be made up of 8 genera and about 900 species of usually monoecious1 trees and a few shrubs of primarily the temperate and tropical parts of the world and then primarily in the Northern Hemisphere. They can be either deciduous or evergreen.

The leaves are simple2, pinnately veined3, variously lobed or entire4 and are placed alternately on their stems. The stipules5 are deciduous, usually falling early and therefore are often not seen.

The flowers are small and inconspicuous and nearly always unisexual and the species are usually monoecious.6

The staminate7 flowers occur in slender catkin-like8 inflorescences or in clusters. There are 4 to 6 sometimes 7 sepals9, no petals and 4 to 40 stamens.
The pistillate10 flowers are situated in an involucre11 and are distributed singly or in small clusters of usually three. There are generally 4-6 sepals and no petals and the ovary is inferior.12

The fruit is a nut either free or fused to a cup-like organ or bur.

The family is an important source of lumber, some edible fruits, cork and many ornamental shade trees.[4 & 25]

The Oaks

Scientific name: Quercus species. Different references estimate large differences in the number of species of oak in the world. Rehder[20] estimates more than 200 species; a book published by the Morton Arboretum[15] estimates about 450 species. At the time of this writing, Wikipedia provided a range of 450 to 600 species.

Plant description: As indicated above, the oaks comprise a large number of species, which from a beekeeping perspective are much alike. Rather than dwell on one or two species, I treat them here as a group, and the photos provided are presented primarily to illustrate the general characteristics of the group and not to indicate that they are of special importance to the beekeeper.

The genus Quercus consists largely of deciduous and evergreen trees and only rarely shrubs. The buds have many overlapping scales, the leaves have short stems (petioles), the veins extending from the mid-vein are arranged like the left and right sides of a feather and the leaves can display a variety of indentations along their edge and are only rarely entire.13

The staminate (with stamens, i. e. male) flowers are arranged on slender pendulous14 catkins, and have 4 to 12 stamens (usually 6) and the calyx15 is 4 to 7 parted. The pistillate (with pistils, i. e. female) flowers either stand alone or are arranged in many flowered spikes.16 The ovary generally has 3 and rarely 4 or 5 locules.17 The elongated portion of the pistil can be either long or short and is dilated on its upper end with the stigmatic surface18 on its inner face. The fruit is a nut, the acorn with which most are familiar. It can be nearly spherical, to oblong or almost cylindrical and is usually surrounded at the base by a cuplike involucre19 that hardens with age. Most of us usually think of this as the cap of the acorn, but while still on the tree, is between the nut and the branch to which it is attached. This ‘cap’ is composed of overlapping scales that sometimes are fused into concentric circles.[20]

Distribution:
Rehder[20] describes the world distribution of the oaks as the temperate regions of the northern hemisphere, and at high altitudes in the tropics south to Columbia in the Americas, and in Eurasia to the Malay Archipelago between Asia and Australia.

Blooming period:
In Michigan the Oaks generally bloom in May or May and June.[3] The blooming period in California depends on the species, the inclusive blooming period being January to August with the majority blooming March to May[26] In the Great Plains, again depending on the species, they bloom March to May, the great majority of them during April and May.[10] This has little, quite probably nothing, to do with honey production (see next topic), but does provide the range over which pollen is produced.

Importance as a honey plant: The early beekeeping literature about whether oaks produce any floral nectar is muddled with much of it probably wrong. Richter[21], writing about California honey plants in 1911 makes the following statement for Quercus agrifolia, Q. densiflora, and Q. douglassii: “Honey and pollen from the flowers”, and for Q. lobata, “Eagerly visited by bees for both honey and pollen.” Following these remarks he makes statements about Q. agrifolia, Q. douglassii and Q. lobata that indicate with favorable conditions bees gather honeydew, often in considerable quantities in the fall. For readers not familiar with the term, honeydew, it is the product of insects, usually with piercing sucking mouthparts, feeding on the plant’s juices and then depositing what passes through their digestive system onto the plant upon which they are feeding. It is this excrement the bees bring back to the hive and process much as they do nectar. While bees probably prefer nectar, when it is limited they will collect honeydew, and the honey in the hive becomes a mixture of products from the two substances. The production of honeydew by these plant-feeding insects is in itself an interesting subject that is described under ‘Additional Information’ below.

In the November 1923 ABJ, George Shafer[24]writes about the galls20 of Dicholcaspis eldoradensis21 working on valley oak (probably Quercus lobata) that were heavily worked by bees and speculates that this was probably what Richter had written about.
G. H. Vansell[27] in his 1931 ‘Nectar and Pollen Plants of California’ says concerning oaks “Most of them give pollen and possibly some nectar for bees”, but then goes on to say “honeydew from the multitude of scale and gall insect inhabitants of oaks is of more importance.” In his summarizing Table 1 under ‘value as a source of honey’ he provides “minor”, suggesting that perhaps he might have thought there was some floral nectar, though not much. The main text of the 1941 Bulletin of the same title by Vansell and Eckert[28] says nothing about nectar and gives much importance to honeydew. In their summarizing table (Table 3) however, they rate the value as a source of honey as minor. My interpretation of this is that they still considered it possible that oak produced some small amount of floral nectar. While this topic in the early literature could be pursued ad nauseam, John Lovell[12] in 1926 in his ‘Honey plants of North America’ states quite emphatically, “The bloom of the oaks is entirely nectarless, since the genus relies wholly on the wind for pollination. There is not a trace of a nectary in the flowers yet there is a very general impression among beekeepers that the oaks are a source of honey. ”Forty years later, his son, Harvey Lovell[11] echoes this statement with “There are over 30 species (of oak) in the United states all of which are wind-pollinated and lack nectaries.” This exact statement is also found in the Goltz 1977[8] version of this writing. I consider John Lovell to have been quite a good botanist and I believe he was probably correct. The flowers produce no nectar.
There remains one other possibility for oaks producing something other than honeydew that would be attractive to bees. Pellett[18] cites H. B. Parks of the Texas Agricultural College as indicating that post oak (Quercus minor22) yields some nectar from extrafloral nectaries.23 While I have found no other indication of this in the beekeeping literature, a quick Google search using “extrafloral nectaries and oak” will indicate that there is a large interest in extrafloral nectaries because they often involve very interesting relationships with ants that use these nectaries as a source of food and attack other organisms that might ‘wish’ to share or simply examine that resource. This has on occasion included one of my fingers. Since intruders might be there for reasons other than the resource the ants are protecting, for example feeding on some other part of the plant or laying eggs on the plant to supply their progeny with a food source, the ants may actually be protecting the plant. In these situations the plant itself would benefit, and there is some thought that the plants may have evolved these extrafloral nectaries for their own protection. The question then becomes, would bees try to rob extrafloral nectaries that were being protected by the ants? My finger’s experience suggests, “not if they were smart bees!” I doubt that bees bring back much nectar from these extrafloral nectaries and this basically leaves only honeydew.
In 1939 Oertel[17] reported on a multiple year study where beekeepers from around the U.S. were asked to provide data on the bee forage in their area. Over the time that the data was collected, 710 beekeepers had provided information at least once for this study. In the material that precedes his state by state table that provided information about states in which particular plants were considered important by beekeepers, he makes a distinction between ‘honey’ from honeydew and honey from floral nectar, but in the text immediately preceding his state by state accounting, he states “The plants that were reported of value to bees for nectar or pollen or both are listed on the following pages.” While this statement seems to preclude honeydew, the data almost certainly was ...

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