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

Aug 27, 2015: Rhododendron falconeri

Rhododendron falconeri

Type in the word "rhododendron" in an image search, and countless beautiful photos of vibrantly-coloured blooms will appear. The same is true when searching through the Botany Photo of the Day archives: Rhododendron 'Cornubia', Rhododendron moupinense, and Rhododendron periclymenoides represent but a few of the beautiful rhododendron flowers that we have featured.

UBC Botanical Garden has a fabulous collection of rhododendrons from Asia and North America. Like many of our visitors, I am amazed at the beauty and diversity of flower forms possessed by this remarkable genus. As I wander the narrow, shaded pathways of the David C. Lam Asian Garden, however, I am just as often struck by the beauty of the rhododendron leaves that I encounter and by the way that these leaves play with the Garden's ambiance. The thick, substantial rhododendron leaves allow brief shafts of light through the canopy, shining a spotlight on random botanical objects that would otherwise pass unnoticed: here, a spot of light touches on the threads of last-year's maple leaf; there, a tiny tip of a pipevine corkscrews brightly against a dark background. Tiny botanical beauties go unnoticed against a wall of fuchsia flowers, but shine against the restrained backdrop of rhododendron leaves.

Of rhododendron leaves, I find those with contrasting indumentum the most captivating. Indumentum is the coating of extremely fine hairs that can be found on the lower surface of the leaves of many rhododendron species, including those of Rhododendron falconeri. Today's photo shows the underside of one of these leaves, which in its entirety measures about 20 cm long and 8 cm wide, is elliptic in shape, and is held on a long petiole (stalk). I am entranced by the pinnate pattern formed by this leaf's strong veins and by the dusting of felt-like, rusty hairs.

The upper surfaces of Rhododendron falconeri leaves are dark green and have been described as curiously wrinkled. A very light coating of hairs, termed tomentum, coats these surfaces and may prevent insect herbivory.

Aug 21, 2015: Parameconopsis cambrica

Parameconopsis cambrica

I have been reading about European poppies in the book Weeds: In Defense of Nature's Most Unloved Plants, so Mats Ellting's (aka mellting@Flickr) recently-posted photo of Parameconopsis cambrica caught my attention. Although the book doesn't cover Welsh poppy specifically (the examples given are all in the genus Papaver, but more about that below), it shares many characteristics with the poppies that do get included, such as plentiful seeds that persist in the soil for a surprisingly long time. Thank you Mats, for posting this gorgeous photo!

Well over 250 years ago, Linnaeus observed that Welsh poppy was similar to the other members of the Papaver species found throughout Europe, and he named Welsh poppy Papaver cambricum. In 1814, Viguer renamed the species Meconopsis cambricum, founding the genus Meconopsis on the basis that its members have a distinct style, rather than a disc-shaped stigma that lacks a style and instead attaches directly to the ovary. Since then, all poppies with styles have been labelled as Meconopsis. The genus has grown to include about 50 accepted species.

Gardeners have always noticed that Welsh poppy is the black sheep of the Meconopsis (or, the yellow sheep, I suppose). The large, Himalayan blue poppies, such as Meconopsis baileyi, are quite challenging to grow whereas Welsh poppies grow under most conditions and even tend to become weedy. Most members of Meconopsis are monocarpic, that is, they die once setting seed, while Welsh poppies perennially produce fruit. All of the Meconopsis come from Asia, while the Welsh poppy is from Europe. Recently, genetic studies proved that Linnaeus (and all of those gardeners) were onto something all along. A study published in the New Journal of Botany asserted that other members of the Meconopsis evolved styles independently of the Welsh poppy, and that its closest relatives lie in the genus Papaver.

Changing Meconopsis cambrica to better reflect its uniqueness, however, was easier said than done. Since it was the founding member of its genus, the Welsh poppy should technically retain the genus name Meconopsis, and all other members of the genus should be moved elsewhere. This proved problematic, as Meconopsis is a well-known genus and many of its members are celebrated horticulturally. Changing all of these species into a new genus would be disruptive and costly to many people. A more palatable solution was proposed by Christopher Grey-Wilson, who suggested the name Meconopsis be retained for all of the Asiatic species, and that a new generic name be created for the Welsh poppy, Parameconopsis cambrica. A full account of Grey-Wilson's reasoning can be found in his beautiful and informative book, The Genus Meconopsis: Blue Poppies and their Relatives (2014).

Aug 19, 2015: Eryngium leavenworthii

Eryngium leavenworthii

Somehow, I have managed to go through life without once noticing a sea holly. When I saw Don McClane's perfectly-captured image of Eryngium leavenworthii, I immediately thought, "what is that, and how can I get one!?". It turns out species of Eryngium have long been prized by gardeners. Seeds of many species, including Eryngium leavenworthii, are readily available. Thanks Don for introducing me to the beautiful sea hollies!

Eryngium leavenworthii is native to south central USA. It is found on limestone or chalky soils of prairies, open woodlands, and roadsides. It is an annual or short-lived perennial species that reaches a height of nearly a meter. Eryngium leavenworthii's claim to fame is its brilliant purple colour. The terminal flower heads are composed of minute purple flowers and bracts (these turn purple as the flowers open). The stamens are electric blue, and the pineapple-shaped flower heads are subtended by an involucre of brightly-coloured lobed spiny bracts. The tips of the flower heads bear a tuft of small spiny leaves that deepen to purple as the flower enters anthesis.

This species is popular with native plant gardeners in its range. It is drought-tolerant and readily grown from seed. Michael McDowell, who blogs about his Texas native garden, suggests planting this Eryngium behind other prairie plants such as little bluestem (Schizachyrium scoparium) since its stem and leaves can get scraggly. Being an annual, it will likely grow in most climates, but will require extra attention in areas with cool temperatures or high rainfall. Plant it in free-draining, slightly alkaline soils for best results. Soils with too much fertility will cause Eryngium leavenworthii to grow leggy and for the leaves to overwhelm the floral display. If you can grow tomatoes successfully, Eryngium leavenworthii will likely work well for you. The seeds should be sown directly in the autumn or after the last frost in early spring.

Aug 17, 2015: Epilobium hirsutum

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Thank you to marianne@Flickr, for capturing the riotous purple of Epilobium hirsutum in bloom. This photo gives a good indication of the density, uniformity, and beauty of a typical patch of Epilobium hirsutum.

Epilobium hirsutum is an herbaceous species that reaches 1 to 1.5 meters in height. It has woolly leaves and stems, hence the name hirsutum (Latin for hairy). The common name for this species, great willow-herb, is inspired by its long, narrow leaves that are similar in appearance to the leaves of willow species (Salix spp.). Epilobium hirsutum produces many showy flowers that are purple and bell-shaped. It has long white stigmas that ripen at the same time as the anthers, making the flowers capable of self-pollination. Before resorting to self-pollination, Epilobium hirsutum flowers hold their stigmas prominently, so that an insect may cross-pollinate them. Should this fail to happen, the stigma on the fading flower curls backwards to touch the ripe pollen held on the stamens. These flowers then form long narrow capsules that contain small seeds attached to long white hairs.

Great willow-herb is native to Eurasia, but is now a common weed around the world. It forms dense, monotypic stands in wetlands and waterways. It is associated with another wetland species, purple loosestrife (Lythrum salicaria). Epilobium hirsutum and Lythrum salicaria strike a seasonal balance - in autumn, the shorter days and colder temperatures favour Epilobium hirsutum while in spring Lythrum salicaria grows more quickly, making up for lost ground. Together, these two species form bright purple, colourful flower displays. Both Epilobium hirsutum and Lythrum salicaria were originally planted as ornamental garden species. Despite their beauty, they should not be planted outside of their native range, as both can aggressively crowd out other wetland species.

Aug 10, 2015: Achillea millefolium

Achillea millefolium

Today's photo features one of my favourite plants of all time - Achillea millefolium, or yarrow. There are many excellent photos of yarrow available online, but I particularly like the contrast between the green and white that Randi Hausken (aka randihausken@Flickr) has captured in today's image.

To call Achillea millefolium a species is incorrect. Achillea millefolium is a species complex, or aggregate, that consists of a set of species that are closely related. The members of the Achillea millefolium aggregate have a combination of different ploidy levels and natural hybridization. The relationships between the members of the aggregate are difficult to reconstruct. Guo, Saukel and Ehrendorfer (2008)(pdf) recount some of the attempts to make sense of the Achillea millefolium aggregate, which include placing all members into one giant species, or conversely, breaking the aggregate down into 40+ micro-species. One way of sorting the Achillea millefolium aggregate is by ploidy level (number of sets of chromosomes in a cell). The diploid (2 sets of chromosomes) taxa are limited to distinct areas in Eurasia and are less variable than the others. Achillea millefolium also come as tetraploids (4x), hexaploids (6x), and octoploids (8x). These species groups are far more variable and have an extensive northern hemispheric distribution. They are found in a wide variety of habitats from deserts to sea coasts, lawns and talus slopes.

The diversity of forms and locations that yarrow occupies is one of the reasons that I love this plant so much. In the period of one day, I can see tall pink yarrow cultivars that I have planted in my garden, the dainty fern-like foliage of yarrow growing weedily in lawns, scruffy yarrow growing along the roadside, and short-stemmed yarrow growing wild along an alpine trail. Although I will likely never understand the evolutionary sequence of these members of the Achillea millefolium aggregate, I can still make use of any of them if I am feeling ill or have been hurt. As a child, my mother would make a tea of yarrow flowers, amply sweetened with honey, anytime that I had a cold or flu. A review on phytochemistry and medicinal properties of the genus Achillea lists many medicinal properties for yarrow, including its use in treating wounds, ulcers, and diabetes.

I imagine that most of the Botany Photo of the Day readers in the northern hemisphere are just as intimately familiar with Achillea millefolium as I am. Those of you in the south are likely wishing I had provided a description of yarrow 2 paragraphs ago! Here it is: Achillea millefolium is a rhizomatous perennial that produces flowering stems .2-1 meter tall. The leaves are bipinnate or tripinnate, and distributed spirally along the stem. They are up to 20 cm long at the bottom of the stem, getting smaller as they approach the top. The Achillea millefolium inflorescence is a panicle corymb of calathidia (it's like a double inflorescence: the composite inflorescence type (calathidium) further arranged in a panicle corymb). It can be white to pink or yellow. What appears to be an individual flower in today's image is actually composed of 3-8 ray flowers and 15-40 disk flowers (a typical characteristic of the Asteraceae). The disk flowers are crowded into the centre of each flower cluster, forming what looks like the eye of the flower. The ray flowers form what look like the petals. These flowers are nested within multiple layers of scale-like involucral bracts.

Aug 7, 2015: Angophora subvelutina

Angophora subvelutina

Today's photo shows a gnarly Angophora subvelutina photographed in its natural range of eastern Australia. Thank you to dustaway@Flickr, who captured a sense of movement and loneliness in the Australian savannah.

Angophora is closely related to Corymbia and Eucalyptus, all three of which are referred to as eucalypts. The distinguishing characteristics of Angophora are opposite leaves and fruit with sharp ribs (as opposed to Eucalyptus' generally smooth fruit). Angophora fruit also lacks an operculum, or bud cap. The name Angophora is composed of the Greek words for goblet (angeion) and carry (phoreo), in reference to the cup-shaped fruit.

Angophora subvelutina is locally abundant in the eastern parts of the Australian states of New South Wales and Queensland. It prefers fertile soils, making it an indicator of good farmland. It is also known as broad-leaved apple (the term apple is used by Australians to refer to any Angophora species). This medium-sized tree has twisted and gnarled branches with flaky, brittle bark. Not shown in today's photo is the lignotuber - a woody swelling of the root crown that provides insurance against disturbance such as fire. If the upper parts of Angophora subvelutina are cut or burnt, it resprouts from buds within the swollen crown. The lignotuber stores carbohydrates that may make a critical difference should the tree lose all of its photosynthetic parts. Angophora subvelutina also employs epicormic buds as part of its fire-survival strategy. These buds within the bark of trees are explained further in a previous post featuring Eucalyptus coccifera.

Mature Angophora subvelutina leaves are blue-grey to dark green, while new leaves are rosy pink. The size, shape, and length of petiole of the leaves varies considerably. The colour of the new leaves, coupled with new growth that is covered in scattered long red hairs gives this species another of its common names, red apple. The inflorescence is prolific. Loose corymbs of small white to cream flowers are held at the tips of branches. These abundant flowers are an important source of honey, and also provide nectar for butterflies and the Queensland blossom bat (Syconycteris australis).

Aug 6, 2015: Physocarpus opulifolius 'Monlo'

Physocarpus opulifolius 'Monlo'

Today's photo features a purple-leaved cultivar of ninebark, Physocarpus opulifolius 'Monlo'. This photo was taken by Anne Elliott (aka annkelliott@Flickr) at Olds College botanic Gardens and Wetlands in Alberta, Canada. Thanks for sharing, Anne!

The wild, eastern North American Physocarpus opulifolius is an attractive species in its own right. It provides interest in the garden nearly any time of year. The tall, arching stems form a vase-shaped bush that can be used in borders, hedges, or as a specimen plant. Abundant, fluffy corymbs of white flowers in late summer are followed by dark glossy red fruits that persist into late autumn (fading to a rosy tan). In winter, the stems take the spotlight. The bark exfoliates in narrow strips, revealing layers of different hues that inspire this species' common name.

The cultivar 'Monlo' takes the ornamental merits of Physocarpus opulifolius to the next level. The selection was discovered growing in a field along with 120000 other Physocarpus opulifolius seedlings at Kordes Nursery in Germany. One seedling had unusual red foliage; its potential was recognized by the nursery owners, who designated it as the cultivar 'Monlo'. Physocarpus opulifolius 'Monlo' offers all of the same gardening qualities as its native counterpart, but in addition boasts deep-burgundy foliage. As you can see from today's photo, the crinkled leaves look particularly stunning when contrasted with this cultivar's pink-tinged flowers or red fruits. The combination of these qualities has earned Physocarpus opulifolius 'Monlo' the Royal Horticultural Society's (RHS) Award of Garden Merit. If you are seeking this cultivar for your garden, it is typically marketed under the registered trademark Diabolo® (though many sources incorrectly treat the trademark name as the cultivar name, or sometimes drop the first "o" from the name).

As a native plant enthusiast, I feel an unjustified sense of pride when a species from my own continent gains international acclaim. It's nice to know that plants that are (at least) similar to species supporting wild North American ecosystems are finding their way into gardens worldwide. Still, a number of studies have indicated that native plant species result in higher insect diversity than exotic plantings (see Wilde, Gandhi and Colson 2014). I wondered, however, whether a Physocarpus opulifolius 'Monlo' planted within the wild ninebark's range could contribute to local ecosystems as much as the native species would. Two entomologists from the University of Minnesota, Emily Tenczar and Vera Krischik, attempted to answer this question. They tested which ninebark plants that specialist ninebark beetles (Calligrapha spiraeae) preferred to eat and lay their eggs on. These beetles were presented with the native Physocarpus opulifolius as well as its cultivars 'Monlo' and 'Dart's Gold'. The ninebark beetles seemed indifferent to whether they were making use of the native species or 'Dart's Gold', but avoided laying their eggs or eating the cultivar 'Monlo'. At least for this species of insect, it didn't matter whether a plant was wild-grown or cultivated. Instead, the species or cultivar's specific characteristics were what made the difference. Tenczar and Krischik posit that the high levels of foliar anthocyanins found in the cultivar 'Monlo' were the likely reason that the beetles favoured the other ninebarks.

How does a gardener considering pollinators and wildlife decide whether to plant native species or cultivars (and if cultivars, which ones?)? The article, Native Cultivars - Good, Bad, and Ugly by Vincent Vizachero provides a straightforward answer. The article suggests staying away from any cultivars that promise "improved insect resistance" (as Physocarpus opulifolius 'Monlo' does). Vizachero also recommends sticking with cultivars that have similar flower shape, berry size and leaf colour as the original species. Sounds like good advice, but I'm not sure I am willing to give up the deep purple leaves of 'Monlo' ninebark in exchange for my region's native ninebark, Physocarpus capitatus.

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