Pollination of Wild White Indigo ~ Baptisia lactea

Wild White Indigo ~ Baptisia lactea (B. alba)

The tall racemes of wild white indigo project above the other prairie forbs and grasses in early spring before these competing plants start to grow. It is statuesque in form, with the blue-gray foliage and light gray, sturdy stems. If you purchase or grow wild white indigo, small seedlings can take a few years to establish before flowering.

Wild white indigo plants grow in open, mesic prairies in full sun.

Worker and queen bumble bees are the primary pollinators of wild white indigo. Their size and strength allows them to pry open the flowers accessing the nectar inside. In a cool spring where the flowers open later than average, more queen visits occur. In an average season, the flowers are visited by more worker bumble bees than queens.

The flowers of wild white indigo are protandrous - the male reproductive organs develop before the female reproductive organs. Flowers open and mature from the bottom upwards on the raceme.

Bumble bees fly towards the upright flower raceme landing on one of the lower flowers in the pistillate (female) phase which typically produce more nectar than those at the top in the staminate (male) phase.

After bumble bees seek out the higher nectar rewards on the pistillate flowers, they work their way up the flower raceme to the upper flowers in the staminate (male) phase. Pollen is therefore transferred during the last stage of their visit on staminate (male) flowers. The bumble bees move on to a new flower raceme carrying pollen with them to pollinate the next staminate (female) flower visited.

A smaller worker bumble bee pries open a staminate (male) flower. Remaining in this position for close to a minute, it rubs its rear legs over the exposed stamens collecting pollen.

Once the flowers are pollinated, an inflated seed pod develops housing the seeds, turning from light green to dark gray over the summer.

The seeds of wild white indigo are heavily predated on by a small weevil, Trichapion rostrum (Apion rostrum). This weevil can be very destructive, consuming most or all of the developing seeds inside a seed pod. Female weevils seek out the pods in June and drill a small hole at the base. Eggs are laid on the pod and using her snout, the weevil pushes them through the hole into the pod.

To save energy and resources, wild white indigo plants often abort pods during ripening, especially those with weevil populations inside. The pods decay and the developing weevils inside die.

References:
Haddock, R. C., & Chaplin, S. J. (1982). Pollination and seed production in two phenologically divergent prairie legumes (Baptisia leucophaea and B. leucantha). American Midland Naturalist, 175-186. Retrieved from http://www.jstor.org/stable/2425307

Horn, S., & Hanula, J. L. (2004). Impact of seed predators on the herb Baptisia lanceolata (Fabales: Fabaceae). Florida Entomologist, 87(3), 398-400.

Petersen, C. E., Petersen, R. E., & Meek, R. (2006). Comparison of common factors affecting seed yield in the congeners, Baptisia alba and Baptisia bracteata. Transactions of the Illinois Academy of Science99, 31-36.

Petersen, C. E., & Sleboda, J. A. (1994). Selective pod abortion by Baptisia leucantha (Fabaceae) as affected by a curculionid seed predator, Apion rostrum (Coleoptera). Great Lakes Entomologist, 27, 143-143. Retrieved from http://insects.ummz.lsa.umich.edu/mes/gle-pdfs/vol27no3. pdf#page=18

Pollination of Dutchman's Breeches ~ A Royal Affair

Dutchman's Breeches ~ Dicentra cucullaria
Dutchman’s breeches flowers very early in the spring typically at the end of April but this year closer to mid-May. The bright white 'pants' look like they are hanging on a clothes line to dry.

Small plants take a few years to establish and flower but it’s worth the wait; plant in small masses for better effect in a woodland garden. The foliage yellows and dies back by mid-June so it's a good idea to inter-plant with later flowering woodland species such as false solomon’s seal to cover the void left after dormancy.

The timing of flowering of dutchman’s breeches coincides with the emergence of overwintering queen bumble bees. As queen bumble bees emerge from hibernation, they fly low to the ground in woodlands searching for appropriate nesting sites in abandoned rodent holes, leaf piles or other dry locations. The low growing, Dutchman’s breeches serves as an important nectar source to be used in the initial provisioning of their nests.

Queen bumble bees have the tongue length, size and strength to pry open the petals on the flowers. As the flower develops, the bottom of the outer petals reflexes revealing the yellow coloration near the opening. This coloration acts as a visual attractant to visiting queens. They land on the side of the flowers grasping onto the outer petals, they also, as pictured in this photo, grasp onto adjacent flowers with their rear legs.

Once they have a good hold, they rotate their bodies in order to access the flower opening, directing their head toward one of the nectar spurs. Pushing their tongues then heads in between the outer and inner petals opens the flowers and allows them to reach the nectar in the spurs. Pollen is brushed onto their head and thorax, as the inner petals are deflected revealing the anthers. Their front legs often grasp the inner petals which helps expose the anthers and stigma and ultimately transfers pollen onto their forelegs.

Pollen also accumulates on the bottom edges of the petals. The inner petals are hinged and when the bee removes its head from the flower, the petals return to their original position. Pollen that has dropped to the edges of the petals is transferred to the middle legs of the bee. The most important pollen placement for pollination of the next Dutchman's breeches flower visited is on the head and thorax.

Other smaller worker bumble bees chew small holes in the two nectar spurs to steal nectar because they are not strong enough to pry open the petals and have shorter tongues than queen bumble bees.

Even smaller bee species such as Cuckoo bees, Nomada sp. and mining bees, Andrena sp. fly around and occasionally land on the flowers investigating them for a potential reward, but none can be accessed.

Like many other spring-flowering woodland plants, the seeds of Dutchman's breeches are dispersed by ants. Ants are attracted to the protein-rich, fleshy elaiosome attached to the seeds. They carry them back to their nests consuming the elaiosome and discarding the fertile seed in their nest's trash pile.

In the absence of queen bumble bees, the flowers of dutchman’s breeches are self-compatible and often self-pollinate.

References: 
Macior, L. W. (1970). The pollination ecology of Dicentra cucullaria. American Journal of Botany, 6-11. Retrieved from: http://www.jstor.org/stable/2440374

Macior, L. W. (1978). Pollination interactions in sympatric Dicentra species. American Journal of Botany, 57-62. Retrieved from: http://www.jstor.org/stable/2442554

Wild Geranium Pollinators & Floral Visitors

Like many spring-flowering native plants, wild geranium flowers have the ability to self-pollinate when no pollinators are present. However, the flower matures to ensure cross-pollination when insects are present, with the row of outer anthers developing on the first or second day after the flowers open, followed by the inner row on the second or third day. The stigma becomes receptive after the anthers have dehisced on the third or forth day.

Bees, flies and beetles visit the flower for nectar and pollen. Nectar is secreted from five glands located between the stamens and sepals. In a study by Bertin et al, bees visiting for nectar were responsible for depositing more pollen than pollen collecting bees. Larger bees such as bumble bees and mason bees are considered effective pollinators because pollen brushed onto the underside of their abdomen contacts the stigma. Smaller bees are able to circle around the base of the stamens feeding on nectar without coming into contact with pollen from the anthers above.

Wild geranium flowers are over one inch in width and extremely showy. Dark lines on the flowers act as nectar guides, showing pollinators the location of the nectaries at the base of the stamens.

Small Carpenter Bees, Ceratina spp.
Smaller bee species circle the base of the flower seeking out nectar without coming in contact with the anthers and stigmas above.

Cuckoo Bees, Nomada spp. 
Wild geranium is a nectar source for this cuckoo bee in early spring. Female Nomada bees lay their eggs in the nests of ground nesting native bees, especially mining bees (Andrena spp.). The cuckoo bee eggs hatch and the larvae kills the host bee larvae and consumes the provisions provided by the host. Nomada bees are reddish-brown to black with yellow or white markings.

Mason Bees Osmia spp. 
Mason bees visit wild geranium for both pollen and nectar. Females land on top of the anthers gathering them together with her legs. Pollen is brushed onto the pollen-collecting hairs on the underside of the abdomen. Wild geranium is an important source of pollen and nectar for mason bees, it flowers when females are provisioning their nests.

Sweat Bees Lasioglossum spp.
Sweat bees visit the flowers to feed on nectar.

Fruitworm Beetles Byturus unicolor 
Long, dense hairs cover the elytra of these beetles where pollen grains attach. Adults emerge from the soil in early spring, feed on host plants (raspberries, blackberries and avens), mate, then lay eggs. Larvae burrow into the flower buds and fruit of the host species and buds drop off or decay. Fruit becomes misshapen and ‘wormy’. Look for adult beetles feeding on the pollen of woodland natives in early spring such as Viriginia waterleaf and wild geranium.


References 
Bertin, R. I., & Sholes, O. D. (1993). Weather, pollination and the phenology of Geranium maculatum. American Midland Naturalist, 52-66. Retrieved from: http://www.jstor.org/stable/2426435

Willson, M. F., Miller, L. J., & Rathcke, B. J. (1979). Floral display in Phlox and Geranium: adaptive aspects. Evolution, 52-63. Retrieved from: http://www.jstor.org/stable/2407365

Plan Now for Spring Pollinators

Tall Beard Tongue Insect Visitors

Tall Beard Tongue ~ Penstemon digitalis
Beard tongue flowers have a large, hairy staminode on the lower half of the tubular flower which restricts access to bees to the flower and helps in pollen deposition. Small to medium sized bees are the most frequent visitors.

Tall Beard Tongue flowers can be white to light pink, sometimes with darker pink to purple stripes which act as nectar guides for bees.

Small Carpenter Bees (Ceratina spp.) visit Tall Beard Tongue flowers primarily to feed on pollen. Their small size allows them to easily climb over the staminode into the tubular flowers to access the pollen on the anthers.

As they feed on pollen, they often inadvertently contact the stigma. The hairs on the staminode keep their bodies held closer to the stigma, resulting in more contact and pollen transfer.

Digger Bees (Anthophora spp.) are frequent visitors to Tall Beard Tongue flowers as well. They are fast moving and visit flowers for a very short time frame compared to Small Carpenter Bees.

Their medium sized bodies and long tongues allow them access into the tubular flower which results in abundant pollen removal as their bodies scrape on the anthers above.

Bumble Bees (Bombus spp.) are not primary pollinators of Tall Beard Tongue. Visiting the flowers for nectar, they are able to reach the nectar reward with their long tongues without having to insert their body into the corolla and come away with pollen on their bodies.

Look for small holes chewed at the base of the flower. Mason Wasps will chew holes to reach the nectar reward without having to enter the flower. Smaller bees will take advantage of these nectar thievery holes.




References:
Attracting Native Pollinators: The Xerces Society Guide, Protecting North America's Bees and Butterflies

The Interaction between Pollinator Size and the Bristle Staminode of Penstemon digitalis (Scrophulariaceae) Gregg Dieringer and Leticia Cabrera R. American Journal of Botany , Vol. 89, No. 6 (Jun., 2002), pp. 991-997

Ohio Spiderwort Insect Visitors

Ohio Spiderwort ~ Tradescantia ohiensis

Ohio Spiderwort flowers open in the mornings for insect visitors, then close up during the heat of the day. The attractive blue to purple flowers have a fuzzy appearance due to the fine hairs on the filaments. Spiderwort flowers from late April through to July.

Bees are the primary visitor, for the abundant pollen in particular. Bumble Bees such as Bombus bimaculatus pictured here collect pollen to provision their nests.

Another common spring occurring bee is the Mason Bee (Osmia sp.), their hairy, blue metallic bodies make them fairly easy to identify.

Mason Bees build nests in cavities, they are the primary nester in bee boards in our area.

Small Carpenter Bees (Ceratina sp.) feed on the pollen of Ohio Spiderwort. They nest in hollow or pithy stems.

A great reason to leave dead, pithy branches such as Elderberry in your landscape to provide nesting habitat for this small bee.

Small Sweat Bees (Lasioglossum sp.) also like the pollen of Ohio Spiderwort. We have a lot of Small Sweat Bees in our landscape, probably because our soils are sandy which is where this ground nesting bee likes to excavate its nests.

Larger Sweat Bees such as this Green Sweat Bee (Agapostemon sp.) are brightly colored and hard to miss. They also nest in the ground.

These are one of the more difficult bee species to photograph, they're fast-moving and not as willing to stay in one place for very long.

The one type of bee that doesn't visit Ohio Spiderwort flowers for pollen is the European Wool Carder Bee (Anthidium manicatum). An introduced species from Europe, females like to visit Ohio Spiderwort for the fine hairs on the buds and flower stalks. Females chew the hairs with their sharp mouthparts, and use the 'wool' to make brood cells.

Syrphid Flies of many types will visit flowers and feed on pollen.

Also look for Bee Flies investigating the flowers.

And where there are bees, there are predators about such as this crab spider, legs outstretched waiting for the unsuspecting bee to stop by.

Ohio Spiderwort is a very adaptable prairie native of medium to dry soils, in full to part sun. It's a great early spring source of pollen for our native pollinators.

Wild Lupine Insect Visitors

Wild Lupine ~ Lupinus perennis 

Wild Lupine is a native perennial of dry, sandy sites in full sun. Flowering from late April/early May into June, the flower color ranges from light blue to dark purple.

Because of its early flowering time, overwintering queen Bumble Bees or their female offspring will visit the flowers. The irregular flower form means that the larger Bumble Bees don't have too much difficulty prying open the lower wing petals to reveal the reward inside.

Bombus auricomis

According to Illinois Wildflowers, there is no nectar reward provided by Wild Lupine, and pollen is forcibly ejected into the faces of bees.

Butterflies and moths will visit the flowers looking for nectar but come away with no reward. I photographed this Hummingbird Clearwing Moth this spring on our Wild Lupine flowers.

I also observed many Mason Bees (Osmia spp.) visiting Wild Lupine flowers this spring. They start with their rear legs prying open the petals, get a start on it opening, then use their mid and forelegs to hold the flowers open.

Wild Lupine and Mason Bees were built for each other, as Mason Bees collect pollen on their abdomens. Perfect for where the fused stamens are located just above the bottom keel, rubbing off some pollen for cross-pollination onto the Mason Bee abdomen.

Look for Mining Bees (Andrena spp.) a ground nesting native bee that emerges in early spring and visits flowers to collect pollen and nectar for nest provisioning.

Small Carpenter Bees (Ceratina spp.) also look in vain for nectar on flowers that have been forced open and are accessible as they cannot pry open the petals themselves.

Wild Lupine is a larval host plant to several butterfly and moth species, the most notable is the specialist Karner Blue Butterfly (Lycaeides melissa) an endangered butterfly.

Native Plant of the Week: Showy Goldenrod ~ Solidago speciosa

Showy Goldenrod ~ Solidago speciosa

Showy Goldenrod is one of my favorite Goldenrod species. Flowering now in mid-September, its tall upright stature and bright yellow conical flowers make it a great addition to any medium to dry site in full sun.

On our gravel hillside, it reaches heights of about 40", in more mesic soils it can get close to 5 feet tall.

Image © Katy Chayka
Minnesota Wildflowers

A native of prairies and woodland edges in sandy to loamy soils. It is rhizomatous, but forms nice, manageable clumps.

The leaves are equally attractive as the flowerheads, dark and glossy green. "In the upper half of the plant, there are often small leaves that develop from the upper axils of the primary leaves; they have a wing-like appearance." (Illinois Wildflowers)

It's also a favorite of bees right now. Many species of Bumble Bees, Mining Bees and Honey Bees visit the flowers.

A Jagged Ambush Bug is waiting patiently waiting for its prey (Honey Bee) to get in 'arm's reach'.

Showy Goldenrod is native to eastern North America, see map for range.

Kartesz, J.T., The Biota of North America Program (BONAP).
2011. North American Plant Atlas. Chapel Hill, N.C.

Native Plant of the Week: Heart-Leaved Aster ~ Symphyotrichum cordifolium

Heart-Leaved Aster ~ Symphyotrichum cordifolium (Aster cordifolius)

Heart-Leaved Aster is a very versatile native perennial. It can withstand well drained, dry soils in partial shade as well as full sun. One of the earlier flowering Asters, it is an important fall plant for pollinators preparing to overwinter.

As the common name suggests, the leaves are heart shaped with a short stalk.

Flower color can range from a pale blue-white to medium blue-purple. It is a tall native reaching heights of 4 feet in richer, moister soils.

The flowers are arranged in branched clusters, forming a slightly cone-shaped flowerhead.

You will find Heart-Leaved Aster in woodland openings or partially shaded understories, as well as in dry, sunny open sites. It will reseed heavily if planted in rich soils.

It is an excellent native perennial to utilize in woodlands after removing an understory of invasive European Buckthorn. It helps keep out other invasive species such as Garlic Mustard from encroaching into the void.

Fall emerging Mining Bees (Andrena spp.) love to visit the flowers, along with Bumble Bees.

Heart-Leaved Aster is native to eastern North America, see map below for range.

Kartesz, J.T., The Biota of North America Program (BONAP).
2011. North American Plant Atlas. Chapel Hill, N.C.