Friday, September 9, 2016

Autumn Bee Plants

A male long horned bee (Melissodes sp.) perched on Madia elegans with a face full of pollen. 
Autumn is here, the days are warm, the nights are cool, and bees and other pollinators are still active. For me this is one of the best times of the year since we can finally get some relief from the intense heat of summer, and the leaves begin to change color on the trees. For bees, particularly honeybees, it is a crucial time to collect as many resources as possible so they can survive the winter. For solitary bees and other pollinators, most of which do not live in colonies or over winter as adults, nutrition is kept up in mating individuals and stores for brood are collected so the species may live on another year. For many of us gardeners, we love to see and support these creatures. This means reducing or eliminating the use of pesticides and providing them with good nutrition: flowers.

Apis mellifera queen mating yard flanked with Madia elegans
As a general rule, native flowering plants (although occasionally less showy) are far more useful to pollinators than exotic plants since the native pollinators have coevolved with them since time immemorial. Foreign plants, even those from a different region of the same state, generally do not attract the same diversity of pollinators, however, they may be highly attractive to a select few pollinators. I personally am not "strictly native" when it comes to gardening, so I grow many nonnative plants. I do appreciate the value and importance of natives, having seen firsthand the pollinators they attract that aren't attracted by exotic plants. This, in a sense, strikes a balance between gardening for conservation and gardening for aesthetics. Of course, for me, I am always gardening for pollinators.

Madia elegans
Madia elegans is one native wildflower that is just beginning to enter gardens. The flowers are open from dusk til dawn, and will remain open longer if grown with a Northern exposure or on cloudy days. They are highly attractive to honeybees and a variety of other bees and other pollinators, though for conservative gardeners they may appear a bit weedy and untidy.

Read more about Madia elegans and its various pollinators (Owen 2016)

Euthamia occidentalis with Halictus ligatus
Euthamia occidentalis is a native golgenrod, occasionally sold in nurseries, and is used for erosion control. It can be grown in damp places, something I have seen firsthand on the bank of the Rogue River. Like the true goldenrods (Solidago spp.) they are highly attractive to bees, as well as various wasps. I observed honeybees and halictid bees visiting the flowers. Sphecid wasps, Prionyx sp. I think, were also seen. Species of Prionyx paralyze grasshoppers as live food for their offspring in underground brood nests.

Cichorium intybus
Chicory is one of those nonnative plants that is found nearly everywhere humans are, a truly successful species. They are closely related to lettuce, and like lettuce have flowers that are open for a single day (often only in the morning) before withering. New flowers open daily, and attract honeybees and other bees, as well as other pollinators (like grass skippers, Hesperiinae).

Cichorium intybus (2015)
Being a composite, each stalk seen in this photo is an entire flower complete with staminate and pistillate parts, while the "petals" are actually sterile ray florets whose purpose is to attract and provide a landing pad to pollinators.

Read more about Cichorium intybus (Street et al. 2013)

Centaurea solstitialis and Apis mellifera
Related to chicory, in the sunflower family (Asteraceae), yellow starthistle is another nonnative plant which is adored by honeybees and beekeepers alike. Unlike chicory, which is unofficially considered to be a benign exotic by most, Centaurea solstitialis is on the noxious weed list in Oregon and at least ten other states and two Canadian provinces. Despite this, it is loved by beekeepers since it gives honeybees a lot of resources to make it through winter, since this region is generally considered to be in a dearth of nectar from mid-summer onward. I challenge this view, considering there are at least a few other plants, native and exotic, which are worked by bees and flower en masse in the latter half of the year (i.e. Madia elegansHypochaeris radicata, the latter another noxious nonnative adored by bees).

An apiary inundated with yellow starthistle
Yellow starthistle is native to southern Europe and western Eurasia, and in some parts of its native and introduced range is considered to be a supreme honey plant as the honey produced from it is one of the most sought and most popular varietal honeys according to some sources. The plants are self-incompatible, thus requiring insect pollinators. Honeybees account for most of the seed set, bumblebees following in importance. The apiary above was surrounded by a portion of uncut starthistle in Ashland, Oregon. The hills of Ashland are completely filled with this invader, showing the true destructive nature of noxious weeds, whose extreme competition outcompete native wildflowers and disrupt the natural balance. And in case you were wondering, I had to work all fifty+ hives in this apiary, and thanks to the thorny inflorescences, it was quite literally a pain in the ass (among other places).

Read more about Centaurea solstitialis (Zouhar 2002)

Cirsium vulgare
True thistles, such as bull thistle (Cirsium vulgare) are considered noxious weeds in Oregon and several other states. It is found in all fifty states of the US, yet native to Europe, Eurasia, and Africa. The plants are worked by honeybees and bumblebees, possibly others, though they often grow in very low density in this area so are not worked judiciously. They are known to grow in dense stands and I would presume that they would be quite covered in bees. The thorns are incredibly sharp and easily penetrate clothing and skin, which I can say is quite painful!

Lathyrus latifolius with a small leaf-cutter bee (Megachile sp.)
Another nonnative weed, quite widespread, the perennial sweet pea was once introduced to prevent erosion in ditches and banks. Fortunately, it is worked by a variety of bees including honeybees, bumblebees (Bombus spp.), large carpenter bees (Xylocopa spp.), and leaf-cutter bees (Megachile sp.). Peculiar, this nonnative pea is the only flower I have seen the leaf-cutters on. Except for the carpenter bees, all the bees I have seen appear to rob nectar by accessing it from above the nectaries rather than passing through the anthers, though these plants may very well be self-compatible like the garden pea since they seem to produce full pods most of the time (if not all the time).

Verbascum olympicum
Mullein (Verbascum spp.), occasionally "cowboy toilet paper" (I haven't, so don't ask), is an ubiquitous roadside weed, probably all over the country. Typically when one speaks of mullein one is speaking of Verbascum thapsus, or common mullein, which has a single flower spike and can reach seven or eight feet in height. A less common species, at least in my area, V. olympicum differs from V. thapsus most obviously by the multi branched inflorescence atop the plant, which attains a similar height. The individual flowers of V. olympicum appear to be slightly larger than those of V. thapsus, and the flowers of the latter seem to close or wither quicker than the former.

Verbascum olympicum and a hidden bumblebee
Both V. thapsus and V. olympicum, in my experience, are decent bee plants, though V. thapsus seems to only be worked in the morning when new flowers open, while V. olympicum seems to be worked all day. Another weedy mullein commonly encountered, V. blattaria, or moth mullein, is only occasionally worked by bumblebees but rarely honeybees, or at least I haven't seen it. All are grown in gardens, sometimes for their medicinal properties (the flowers of V. olympicum and V. thapsus are used for tea, and the plants are a source of water soluble saponins and mucilage).

Oenothera elata ssp. hookeri
The tall evening primrose, similar to some of the species native to Oregon, is one of many species grown in gardens. As the name implies, the plants can get really tall, up to four feet in the case of the plant photographed. The flowers open at dusk and remain open until morning when they wither. Though each flower is only open one night, new flowers open daily. They are primarily pollinated by large crepuscular sphinx moths (Sphingidae), some have visited this plant on more than a few occasions though I was unable to attain a photo. Honeybees adore it, as you can probably tell, and can be seen visiting the flowers as they open on warm nights, or in the morning before the flowers wither. There are hybrids of some of the smaller oenotheras available (i.e. Oenothera kunthiana), though they do not appear to be as attractive to pollinators in my garden.

Asclepias fascicularis and Apis mellifera
Many milkweeds are useful bee plants, though the flowers of some species can pose a threat to bees and other pollinators (more on that later). Milkweeds are important honey plants in much of the US where they are common. They are also paramount to the survival of many species of butterflies, including the monarch (Danaus plexippus) and other milkweed butterflies (Danainae) since the caterpillars of these butterflies are completely dependent on them for sustenance. Certain species of moths and a few true bugs are also dependent on milkweeds for survival.

Read more about milkweeds as honey plants (Krochmal 2016)

Apis mellifera with pollinia on her hind foot
Milkweeds are peculiar plants for a variety of reasons. For an amateur botanist, I find their breeding system intriguing. The most notable feature of this, I think, is that the pollen is in the form of pollinia, as is found in orchids, where the pollen from each anther is composed into a single sticky mass. This mass adheres itself to the foot, or anywhere on the pollinator before being hooked onto the "claws" surrounding the pistil. Some unfortunate pollinators whose feet have pollinia attached become stuck themselves on these hooked appendages (called horns) and not having the strength to escape, die of dehydration or something similar. Butterflies, often being larger and more powerful fliers, can probably escape the horns quite easily, but bees, beetles, and wasps have been found hanging, dead, on the flowers of some species.

Read more about the Fatal Attraction of Milkweeds (Chen 2006)

Croton setigerus
In dry sunny fields, an inconspicuous plant in the Euphorbiaceae forms tight grey-green cushions of hairy foliage and tiny inconspicuous flowers. This is Croton setigerus, or turkey mullein, found in much of the Western US in dry hot sites. It is occasionally worked by honeybees, and claimed to produce a "thick amber honey."

Read more about Croton setigerus (Owen 2016)

Trichostemma lanceolatum
Trichostema is a genus in the Lamiaceae, or mint family. A few of which are notoriously bee pollinated, such as the perennial California native T. lanatum, woolly blue curls, which is widely proclaimed to be a good honey plant. In my region, the annual T, lanceolatum is a somewhat locally common plant that grows in poor soil with low grasses and other small forbs. In my experience, it is more frequently visited by skippers (Ochlodes sylvanoides) who appear to be a good fit for the plants highly elongated reproductive structures.

Ochlodes sylvanoides on Trichostema lanceolatum
Pollinator visitation, it seems, is a highly regionally specific variable. This has been seen in many other plants, and can readily be studied by any gardener who grows nonnative plants. In the case of Trichostema, where I have witnessed butterflies, many other people have reported seeing various bees visit the flowers of T. lanceolatum and there is similar literature on bee pollination of T. lanatum. Aside from bees, hummingbirds have been observed on some species, probably another regionally variable observation. To me, this speaks of the adaptability of some species to overcome the boundaries of others, in this case perhaps an inadequate supply of bees (not specifically due to bee losses, but maybe the normal ebb and flow of native bee activity in this area, correlating with the diversity, or lack thereof, of flowering plants at any given time).

Read more about Trichostema lanceolatum (Owen 2016)

Nepeta cataria and Bombus vosnesenskii
In the garden, mints and their relatives are a sure thing when it comes to bee plants. I do grow a variety of mints, all in one corner of the yard since they can be so invasive, and the flowers do attract a variety of bees. I prefer the more well behaved mint relatives, such as Agastache and Nepeta. Common catnip is a short lived perennial that has survived with little care at the border of my garden for four years now. It was started by seed scattered onto disturbed soil and watered for the first year. Now it is four feet tall and covered in small flowers. Many species of native bee are attracted to the flowers, such as Lasioglossum and Bombus vosnesenski. Honeybees also adore the flowers, there may be upwards of fifty bees on this single plant at any one time.

Thymus serpyllum 'Elfin' with Apis mellifera
Another "mint," thyme is always attractive to honeybees. The particular selection T. serpyllum 'Elfin' appears to be later blooming than the others in my garden, and is an excellent plant in my small rock garden. Thyme is the source of the thymol, an antimicrobial compound used for the control of varroa mites (Varroa destructor) among other things. There is a folk tale that where thyme is grown for seed at the field scale the honeybees nearby are free of mites. I cannot speak to the legitimacy of this claim, but the notion that very small quantities of thymol or other mite-repellent compounds are found in the nectar is not without merit.

Aerial yellowjacket (Dolichovespula arenaria), bald-faced hornet (D. maculata)
While talking about autumn bee plants, it is worth noting some of the bees cousins that are also highly active at this time. Aerial yellowjackets and bald faced hornets (both in the genus Dolichovespula) are predatory social wasps which build enclosed paper nests in trees or sometimes under overhangs of human made structures. At best, they are predators of garden pests such as tomato hornworms (Manduca quinquemaculata) and others, but at worst they are bee predators who can destroy weak honeybee hives. For strong hives they are merely a nuisance.

Practices to help your hives protect themselves include using the smallest opening of an entrance reducer, maybe a one inch entrance hole, and feeding your bees (inside the hive is best, i.e. hive top feeders or some variant) so they build in number and strength to ward off any potential intruders. Yellowjacket traps can be useful where they are very populous, but I would suggest using a hot dog or lunch meat as bait rather than the commercially available bait. I don't usually condone the killing of hymenopterans, even wasps, but to be sure with simple traps (a chemical free approach) their populations will not be devastated and they will probably bounce back the following year.

When your cousin shows up at the party uninvited...
...and disembowels your family.
It happens.

Colchicum 'Lilac Wonder' with a carpenter ant (Camponotus sp.)
To avoid ending on a gruesome note, here is one more good group of bee plants: Colchicum. Sometimes referred to as the autumn crocus, this name is a poor representation of the genus since there are autumn, winter, and spring blooming species in both Colchicum and CrocusColchicum, unlike Crocus, grows from a toxic structure that is like something between a bulb and a corm, quite unique, although typically considered to be a corm. Crocus on the other hand grows strictly from a corm and is not toxic, in fact it is practically edible and it is eaten by rodents, deer, turkeys, and slugs. Colchicum is virtually pest free, due to the toxins within the plant. Most of the commercially available colchicums are the autumn blooming types. These tend to flower in the fall, and send up leaves and seed pods in spring. I've grown colchicums for three years, and honeybees seem to adore them.

Colchicum cilicicum
I grow four varieties including three fall blooming and one spring blooming although the spring blooming type hasn't grown to flowering size yet. The first variety I attained was the hybrid C. 'Lilac Wonder,' a commonly available and very popular large flowered hybrid supposedly between C. giganteum and C. bornmuelleri (both sometimes considered synonyms of C. speciosum), bred sometime in the early 1900s. I also grow C. speciosum, which has slightly smaller flowers and is shorter, but equally if not more beautiful.

Colchicum cilicicum
Of the few colchicums that I grow, C. cilicicum is by far the most floriferous and longest blooming, thus the best for bees. The individual flowers don't last very long, but C. cilicicum sends up new flowers in succession for a few weeks. Despite there being so few of these flowers, there is a continuous stream of honeybees visiting them for both pollen and nectar. I imagine a field full of Colchicum would be quite active with bees of various types. I would do just that, but the cost of these large bulb/corms is somewhat prohibitive for me. I am attempting a few species from seed, and have a hopeful view of the future.

Oenothera elata ssp. hookeri with six honeybees

There are many other fall blooming plants that may be excellent bee plants. Some recommended by others include Aster spp., Caryopteris spp., Clematis ternifolia, Epilobium spp., Eutrochium spp., Hylotelephium spectabile, Lythrum salicariaPerovskia atriplicifoliaPycnanthemum flexuosum, Rosmarinus spp., Tetradium daniellii, Vernonia altissimaVitex agnus-caste, and no doubt many others. I'd love to hear about more bee plants, put them in the comments (with your location for context)!

Sunday, September 4, 2016

Trichostema lanceolatum

Trichostema lanceolatum is pollinated primarily by woodland skippers, Ochlodes sylvanoides. (2016)
Most plants, without question, are first seen, but some are first smelled. While taking a walk through a local woodland clearing one day, a sudden strong scent of gasoline or turpentine wafted into my face. It had perplexed me for some time, until I discovered that the origin of the scent was from a plant. I have come to look for this plant every fall, as it is one of the last native plants to bloom here in the Rogue Valley of Southern Oregon (or at least the last to bloom in my neighborhood).

Trichostema lanceolatum (2015)
Trichostema lanceolatum Benth. (Lamiaceae, mint family), or turpentine weed, is an annual Western native from California north into Washington. The plants grow to a height of around ten inches, often branching from the base. The leaves are of a narrow and tapering to a point at the tip (hence "lanceolatum" or lance shaped). The entire plant is covered in dense hairs that secrete a resinous oil, the source of the strong scent which I think is more akin to gasoline than turpentine (or camphor, as another common name suggests).

Trichostema lanceolatum (2016)
The fascinating flowers of turpentine weed are one of the features that make this genus so interesting to me. A related species, Trichostema lanatum, are known as blue curls, presumably named for the flowers. The anthers and stigma are arched out away from the flower, awaiting contact with a pollinator (seen in photos far below).

Trichostema lanceolatum with seed pods (2015)
Flowers are borne on a type of inflorescence called a cyme. Multiple flowers bloom at once, moving up the stem as they seem to produce only a limited number of flowers per cyme. Each flower produces up to four nutlets which fall and germinate the following Spring.

Trichostema lanceolatum (2015)
Trichostema lanceolatum (2015)
Visible here is the flower structure, the anthers have yet to fully expand, or they have been damaged in some way and are deformed. You can also see the dense hairs, possibly serving multiple purposes. As seen in Madia elegans, the resinous hairs (or trichomes) probably help the plants retain moisture during the heat of Summer.

Trichostema lanceolatum variability (2015)
There is some variation in plant height and flower color. They range from a pale lilac to a deep lavender. Height is also highly variable, as well as branching. Some plants grow no taller than three or four inches with a single branch while others grow to twelve inches with over twenty basal branches. Competition from grasses or other plants probably have a lot to do with this, the largest specimens I have seen were bordering a gravel road and thus nearly completely free of competition as the compacted decomposed granite is too harsh for other plants to grow.

Trichostema lanceolatum (2015)
Many of the plants lean generally towards the South, the flowers all being arranged more or less on the same side. For perspective, the South is where the sun is as the days shorten. In winter, the southern exposed sites are the only places to receive a full day of sun, while exclusively northern exposed sites are permanently shaded through winter's entirety.

Trichostema lanceolatum (2015)
The habitat is best describes as hot, with what is suspected to be nutrient deficient soil, possibly serpentine (though I do not believe this plant is an indicator of serpentine). The oils secreted by this species and others have toxic properties to other plants, reducing competition. This could explain why the areas I have found them growing are so sparsely vegetated while the surrounding area is (comparatively, for summer) "lush." Growing in poor soil is also a technique some plants capitalize on since there is less competition by other plants.

Trichostema lanceolatum (2015)
Trichostema lanceolatum (2015)
Pollinators on T. lanceolatum (2016)
I have observed few native blooming plants in the area at this time of year, limited to Madia elegans, Achillea millefolium, and Eschscholzia californica, aside from the Trichostema. The most common flowering plant here, seen in fields everywhere, is the invasive European native Daucus carota, the wild carrot. This leads me to ask the question, is that all that native pollinators had to forage on? Were there once other wildflowers here for native bees, or is the near end of the pollinator season naturally deficient in native wildflowers, corresponding to lowered numbers of active native pollinators late in the growing season? Perhaps before European settlers made this their home, the few native plants that were blooming were more widespread.

Ochlodes sylvanoides (2016)
The most common pollinators of this species were without question woodland skipper butterflies, Ochlodes sylvanoides. Woodland skippers were numerous and frequently visited many flowers on each plant and on multiple plants, suggesting they may be the primary pollinators of T. lanceolatum in this region. I have spent hours observing these plants in different locations over the past two years, and the woodland skippers were and still are the most frequent and numerous pollinators to visit.

Last year I had assumed these butterflies to be primary pollinators of T. lanceolatum due to the morphology of the flower, the arching reproductive organs make contact with the top of the thorax nearly every time the skippers land on the flowers to feed on nectar. Pollen was visible on their backs while at rest, confirming my assumptions.

Ochlodes sylvanoides (2016)
An interesting characteristic of the flowers of Trichostema lanceolatum is that the reproductive organs swing down onto the body of the pollinator when they land on the flower, causing pollen to be transferred. When the pollinator departs, the stamens and stigma return to their original position.

Ochlodes sylvanoides (2016)
The woodland skipper is active in the fall. Being grass skippers (Hesperiinae) they use host plants in the grass family (Poaceae) including Bermuda grass (Cynodon dactylon), canary grass (Phalaris sp.), wildrye (Elymus sp.), and wheatgrass (Agropyron sp.) though that is not a complete list. They are native to the Western US as far east as North Dakota and north from British Columbia to Saskatchewan. During their relatively brief adult lives, O. sylvanoides mates, imbibes nectar, and lays eggs which hatch in a matter of weeks. First instar caterpillars hibernate through winter, complete their feeding in the spring, diapause in summer as fully grown caterpillars, then build their chrysalis and pupate til emergence in the fall.¹

Ochlodes sylvanoides with pollen on the thorax (2016)
The woodland skippers thorax, in my observations, made contact with the reproductive parts of the majority of the Trichostema lanceolatum flowers they alighted on. In a few instances when the skippers were at rest I was able to observe more closely and noted pollen on the throax of most, as seen in this photo. Crossing of pollen from one plant to the next is a highly likely scenario considering the rate at which these butterflies moved between plants.

Trichostema lanceolatum with a tiny hymenopteran (2015)
During my observations, I observed few bees visiting Trichostema lanceolatum, though this was uncommon. Small solitary wasps, Philanthus crabroniformis, though never landing on any of the flowers, had been active near the ground in the midst of the Trichostema. I suspect they have nests around and were hunting small sweat bees, and that in the absence of me they may visit the flowers too.
Small hymenopteran, magnified
I did, although rarely, witness a few different types of solitary bees visit a few of the Trichostema flowers. The photo of a tiny hymenopteram (above) was a happy accident because I did not see it when I took the picture! Difficult to tell from the photo whether it is a bee or a small wasp. I have on a few brief observations seen what may be either anthophorine or eucerine bees visit the flowers, far too swift for me and my camera.

Trichostema lanceolatum (2015)
I have received the testimonies of others that bumblebees or perhaps large carpenter bees also visit the flowers, and appear to fit morphologically. I don't doubt their effectiveness as pollinators, in fact the "buzz pollination" of large native bees is highly effective for the pollination of many natives (particularly those with very sticky pollen, released only by the intense vibrating of the wing muscles). But I did not witness any large bees visit the flowers during my initial observations. Such is the variability of time and place. Honeybees may visit the flowers, but this is extremely rare in my observations.

Trichostema lanceolatum (2016)