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Botany Photo of the Day
In science, beauty. In beauty, science. Daily.

Apr 30, 2015: Pinus thunbergii

The stately Pinus thunbergii is deserving of attention any day, but last week the male cones were resplendently releasing pollen, and I thought it made for a good opportunity to discuss reproduction in the Pinaceae . It took me a while to get a good photo of the pollen grains blowing away, as I had to use one hand to brush the male cone while holding the camera steady with my other hand. I didn't manage to get any that were in perfect focus, but at least with this photo you get the general idea.

Pinus thunbergii, or Japanese black pine, is a gymnosperm. Gymnosperms have exposed ovules that become seeds (unlike the angiosperms, or flowering plants, that have ovules and ovaries that eventually become seeds and fruit). More specifically, Pinus thenbergii is classified as a conifer and, like most of its kin, it has a compounded female cone, formed from a bract and an ovule-bearing scale (the Taxaceae, also conifers, are exceptions to this rule). All conifers have a reproductive strategy that involves female cones as well as male microsporangiate strobili, which, for lack of a better common term, are often called male cones.

Today's photo shows the male cone of a Pinus thunbergii plant. These male cones are 1-2 cm long, and grow in clumps of 15-20. They release large amounts of pollen grains that have two bladder-like wings which help the pollen reach a female cone. Unlike angiosperms, gymnosperms have not developed relationships with pollinators that allow them to move pollen accurately. Pinus thunbergii plants must release vast amounts of pollen into the wind, so that a lucky few microgametophytes will land on one of the tiny, red female cones, or macrosporangiate strobili. The female cones produce a sticky fluid called a pollination drop, which traps the pollen and, as it dries, draws it into the cone. The pollen is stored within the cone, dormant, for a period of one year while the female gametophytes (megagametophytes) develop, two to a cone scale.

During the second year, sperm from the pollen fertilizes the egg in the megagametophytes. By the beginning of the first year, the female cones are greenish-black and tightly closed, as shown in this photo from a previous BPotD post. Paired winged seeds begin to form at the base of each cone scale, and the 7cm long cones begin to turn brown. At the end of the second year, the cone scales will have opened and the mature winged seeds will have blown away, in the hopes of starting the cycle anew.

For more information, the Ohio Plants website has an excellent post on conifer reproduction, which covers Pinus as well as many of the other conifer taxa found in Ohio.

Apr 29, 2015: Bonnemaisonia hamifera

Last month, one of our readers pointed out that I share a last name with a famous 19th century phycologist, Théophile Bonnemaison. I am pleasantly surprised to realize that Théophile was the namesake of not only a genus, but also a family and even an order! I don't know whether I am distantly related to the French naturalist, but it nevertheless brings me a smug pleasure to write about the algae Bonnemaisonia hamifera, of the family Bonnemaisoniaceae, of the order Bonnemaisoniales. I am indebted to Ignacio Bárbara, who kindly sent me the ethereal images of this species that he posted to the Algaebase website.

My smugness has dissipated now that I have realized that, unlike my potential ancestor, I know nothing of algae. I have had to learn that Bonnemaisonia hamifera, commonly called Bonnemaison's hook weed, is a member of the Rhodophyta, an ancient division of eukaryotic algae (aka red algae). According to the online Encyclopedia Britannica, red algae "have some of the most complex life cycles known for living organisms". Please bear with me as I blunder my way through the life cycle and characteristics of this beautiful algae.

Like other red algae, Bonnemaison's hook weed displays alternation of generations; the gametophyte generation occurs in the spring, is bright red, can reach up to 20 cm in length, and forms hooked branches that allow the free-floating plants to attach to other floating algae. Ignacio's first image of the feathery fronds clearly shows these hooks. When fertilized by a male spermatium (which is carried by ocean currents), the female gametophyte will form a fruiting structure called a cystocarp, (see the green blobby bits on the second photo featured today). Fertilization occurs frequently in Japan, where this species is thought to have originated, but most specimens found in European waters are sterile.

The fruiting structures of Bonnemaison's hook weed produce and release tetrasporophytes which form the diploid generation for this species. These tetrasporophytes are so morphologically unlike their parents that they were placed in their own taxon, Trailliella intricata. The Trailliella intricata phase appears as red cotton tufts measuring 25 mm in diameter (photos in righthand sidebar on that page). These tetrasporophytes can occur year round, but are most common from October to March, and are found on hard substrates and human-produced structures.

Bonnemaisonia hamifera has spread to most regions of the world, likely transported on the hulls of ships. Its gametophyte form competes with native algae in low tidal pools. Ironically, it releases a chemical substance that is being studied as an anti-fouling agent to protect ship hulls. Perhaps this substance will some day be used on ships to prevent Bonnemaisonia hamifera from further spread.

Apr 28, 2015: Claytonia virginica

Claytonia virginica

This stunning photo of Claytonia virginica was taken by Bruce Brethauer (aka Glochidman@Flickr), a frequent contributor to Botany Photo of the Day. It is easy to imagine why the common name for this flower is eastern spring beauty; it is one of the first wildflowers to bloom in its eastern North American range, just as the western spring beauty (Claytonia lanceolata) is among the first bloomers here in the west of this continent.

Claytonia virginica is an ephemeral herbaceous perennial found growing in dense clumps in moist meadows and woodlands. In the spring, eastern spring beauty corms send up multiple stalks--the greater the number of stalks, the larger the corm--each bearing several flower clusters. The pale pink flowers measure 8mm across and have 5 petals, 2 green sepals, 5 stamens with pink anthers, and a pistil with a tripartite style. Until recently, Claytonia virginica was most often placed in the purslane family, the Portulacaceae. DNA studies have recently confirmed that Claytonia is better separated with other close relatives into the Montiaceae.

Eastern spring beauty is a myrmecochore: its seeds are dispersed by ants through a mutualistic relationship. Claytonia virginica seeds have a protein and lipid-rich structure attached to them, produced specifically for the ants that will collect the seeds and bring them to their nests. This nutritious structure, termed an elaiosome, is fed to the ant larvae. Once the larvae have finished their dinners, the seeds are placed into the ant's refuse area, which provides a rich and protected growing environment for Claytonia virginica seedlings. Myrmecochory is increasingly regarded by ecologists as an important ecosystem driver, but this has not always been the case. As late as 1975, an overview of ant-plant mutualism posited that ants played little role in seed distribution, but by 1981 a study examining myrmecochory in West Virginian forests (part of Claytonia virginica's range) found that about 30% of herbaceous flora had seeds distributed by ants (see Beattie and Culver in Ecology). It's worth pointing out that while eastern spring beauty's seeds are distributed by ants, its flowers are pollinated by other insects. Andrena erigeniae, a small bee native to eastern North America, pollinates only Claytonia virginica and the closely-related Claytonia caroliniana.

Another common name for Claytonia virginica is the 'fairy spud', owing to the corm that tastes like a small potato when cooked. Early settlers frequently ate this small 'spud', and also ate the young leaves as a salad green. The spring beauties -- including Claytonia virginica, Claytonia caroliniana, and Claytonia lanceolata -- were important foods for the indigenous peoples of North America, and the western Claytonia lanceolata has been particularly well--studied. In the book, Biodiversity and Native America, a quote by the late Lil'wat elder Baptiste Ritchie describes Claytonia lanceolata corms that were as large as a fist in areas that were being intentionally burned by the residents of Mount Currie, near Whistler, BC. These corms were harvested in large quantities and stored for winter use. It's not clear whether traditional management techniques were also used to tend Claytonia virginica patches.

See also a previous Botany Photo of the Day entry about a related species, Claytonia perfoliata.

Apr 22, 2015: Fissidens obtusifolius

Fissidens obtusifolius

This is the first entry that I am publishing myself (Tamara). Daniel will be going away on a well-earned vacation, so I will be the web guru for this coming month. Hopefully I manage to keep the entries posting smoothly!

Today's photo shows the beautiful blunt-leaved pocket moss, or Fissidens obtusifolius, taken by Robert Klips (aka Orthotrichum@Flickr). Robert has been posting so many great photos to our Flickr site that this is the second entry in a row featuring his work. Thanks Robert!

Fissidens obtusifolius is a member of the Fissidentaceae, a family containing 450 species, all within the genus Fissidens. Members of the Fissidentaceae are set apart from similar taxa by two determining features. Firstly, they have distichous leaves, meaning that the leaves are arranged in two vertical rows on either side of the stem. Secondly, they have equitant leaves; the bases of the leaves overlap those growing above them. Both of these characteristics can be seen in Robert's photo, but if your eyes are not eagle-sharp, you might appreciate the magnified image of blunt-leaved pocket moss at the Ohio Moss and Lichen Association website. The ovate to oblong, broadly obtuse leaves have inspired Fissidens obtusifolius' species name; these leaves are about 1mm in length and have no teeth.

Fissidens obtusifolius is found in eastern North America on wet limestone and limestone-bearing sandstone. It is almost always found near water, or in the recesses of wet cliff faces. I love that Robert's photo makes the scale of this species ambiguous. I have the image filling my computer screen, making it look showy and extravagant (for a moss), but in reality this moss is easily-overlooked and reaches a height of only 1 cm. Thanks, Robert, for taking the time to notice the little things!

Apr 20, 2015: Cirsium discolor

Cirsium discolor

An entry from BPotD Work-Learn student Tamara Bonnemaison today, who writes:

Thank you Robert Klips (aka Orthotrichum@Flickr) for this photo of a Cirsium discolor flower covered by soldier beetles (Cantharidae spp.) and a bumblebee (Bombus fervidus). I love this image because not only does it show how stunning the flowers of field thistle are, but also how important this species is to many insects.

Thistles often get a bad rap. In some states of the USA (e.g., Arkansas and Iowa), all species of Cirsium are listed as noxious weeds, regardless of their origin (native or not). Before becoming a student, I ran a small vegetable farm in the Fraser Valley of British Columbia. There, I witnessed firsthand how just a few individual Cirsium arvense plants could soon turn into a field full of the prickly weed. Even the frequent sight of American goldfinches (Spinus tristis) flitting from one seed-filled thistle to the next was not enough to compensate for the many times that I grabbed a handful of Cirsium arvense leaves along with the carrots I was harvesting.

Cirsium discolor, or field thistle, is frequently found on human-disturbed sites such as agricultural fields and roadsides. It has a pink (occasionally white) inflorescence, composed of many narrow, tube-shaped flowers billowing out from a narrow base. Most often a biennial, it grows as a basal rosette in its first year, then sends up a light green branched stem during the second year of growth. The stems have white hairs and do not have spines, while the alternate leaves are spiny, pinnately-lobed, green on the upper surface and pubescent on the lower. Field thistle closely resembles the invasive Cirsium vulgare, and the United States Department of Agriculture's Natural Resource Conservation Service (PDF) urges us to become familiar with the different types of thistles so that we may differentiate between noxious Cirsium species and the native thistles that are important to many North American insects and other wildlife. Any easy way to distinguish Cirsium discolor from Cirsium vulgare is to look for the white, pubescent underside of field thistle's leaves.

Field thistle is native to most parts of eastern North America, and is an important food source for many wildlife species. Native bees, in particular bumblebees, are important pollinators, as are many butterflies, sphinx moths, and bee flies. Birds eat the seeds (goldfinches are particularly well-known for this) or use the fluffy white hairs on the achenes to line their nests.

The soldier beetles shown in Robert's photo are likely enjoying the thistle's abundant nectar, and it looks like the beetles on the lower right are enjoying more than just nectar. Fitz Clarke, on the Skidaway Audubon blog, recounts seeing soldier beetles fighting to mate with females on Cirsium discolor blooms, each of which had claimed her own thistle flower. I know I shouldn't anthropomorphize insect procreation, but it does sound rather romantic!

Apr 15, 2015: Arctostaphylos canescens

Arctostaphylos canescens

The photograph for today's entry is courtesy of manzanitas and conifer enthusiast, Michael Kauffmann. Michael is the person behind Backcountry Press, an "independent publisher of web and print media whose themes explore natural history, ecology, and the western [North American] landscape". Complementing previous excellent works on the conifers of western North America, Michael and co-authors are soon to release a new book, Field Guide to Manzanitas: California, North America, and Mexico. I pre-ordered a copy for the Garden today, and am very much looking forward to it.

Michael also gave his permission to quote part of a recent blog posting he made (Manzanita Country), and it serves as a good introduction to today's posting. Michael writes:

"Manzanitas are the "rock stars" of woody shrub diversity in California, reaching this status by way of amazing adaptability to the varied environments within the California Floristic Province. Most manzanita species depend upon fire for their regeneration and, while found on a wide variety of substrates, preferred soils are typically shallow, rocky, and/or nutrient poor. Like many other California evergreens (including my beloved conifers!) the hardy manzanitas have benefited from environments wherein competition from many plants is reduced and their own adaptability to poorer growing sites allows them to thrive. This, somewhat ironically, has made the unassuming "little apple" the most species-rich shrub genus in the California Floristic Province."

Thanks for sharing, Michael.

Arctostaphylos canescens, or the hoary manzanita, ranges from southwest Oregon south to California's San Luis Obispo County. There are historic records from San Diego County, but I would guess the species has been extirpated there since the last record was from 1903. This erect shrub ranges in size from 0.3 to 3m. The epithet canescens is in reference to having the property of being canescent (a good way to extend a Scrabble word), which is defined as "growing white, whitish, or hoary", or in particular, "having a fine grayish-white pubescence". These small hairs cover much of the plant: the leaves, the inflorescences (including inside the flowers, apparently -- I will have to look for this), and the fruit (many more photos available from CalPhotos: Arctostaphylos canescens).

Members of Arctostaphylos are often very photogenic, and have previously been featured on BPotD, including: Arctostaphylos pallida, Arctostaphylos nevadensis (with a great summary of the genus), and Arctostaphylos columbiana.

Apr 10, 2015: Dianthus 'Moondust'

Dianthus 'Moondust'

Tamara Bonnemaison, BPotD Work-Learn student, writes:

Today we are featuring a very unusual taxon--one that you may have seen recently at the grocery check-out line, but have probably never seen growing: a genetically-engineered carnation by Florigene® known as 'Moondust'. Thank you to Martin Hieslmair and Ars Electronica@Flickr for sharing the photo.

Dianthus caryophyllus, the wild progenitor of many (all?) cut flower carnations, produces a pink flower. Careful breeding has yielded cultivated varieties of bright white, red, yellow and even green carnations. These colours, although not exhibited in wild, represent part of the natural carnation palette, which is dictated by two pigment types: the carotenoids and the flavonoids. The carotenoids provide yellow and orange pigments. The flavonoids are water-soluble pigments, and they can be broken down into three types: the cyanidins that yield red and magenta carnations, the pelargonidins that give us orange, pink, and red carnations, and the delphinidins, which, in theory, would produce blue or purple carnations, if carnations had any.

Since carnations lack delphinidins, no amount of traditional breeding will result in purple or blue varieties. The floral trade has overcome this limitation by simply immersing freshly-cut carnation stems in tubs of blue dye. White carnations are easily dyed, and dying carnations is a great science experiment to teach about capillary action. Roses also lack delphinidins, and are occasionally dyed blue in the same way.

Recently, geneticists have accomplished what breeders could not; the flower company Florigene® has genetically-engineered a series of purple carnations by implanting a carnation with a delphinidin-containing petunia gene. Florigene's 'Moondust' carnation was introduced to limited commercial markets in 1996, becoming the first genetically-modified flower to be available commercially. These purple carnations do not carry the magnitude of health and environmental concerns as many other genetically-engineered crops do: they are not consumed, rarely produce seed, and do not re-grow vegetatively, so the risk of the plant or the genes spreading beyond human control is considered by many regulatory agencies to be small. This has helped make it possible for Florigene to introduce its blue flowers without much public debate.

Georg Tremmel and Shiho Fukuhara think 'Moondust' carnations should become part of the public dialogue about transgenic plants. In a project titled "Common Flowers/White Out" (also see Common Flowers/White Out project (pdf)), Tremmel and Fukuhara experiment with turning a purple carnation back to white by genetically-modifying the Florigene flower to its original white-flowered form. This work was featured at the Ars Electronica Centre in 2013, but I have not been able to find out if Tremmel and Fukuhara were successful with their reverse-engineering.

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