« Previous Day: Sempervivum 'Othello' |
Main
| Next Day: Sparganium emersum »
Nov 20, 2009: Caltha leptosepala var. leptosepala
Nov 21, 2007:
Adansonia digitata
Nov 21, 2006:
Juncus sp.
Nov 21, 2005:
Nerine pudica
July 15, 2009 : Hydrangea aspera subsp. aspera 'Macrophylla'
Interested in subscribing? Visit the main Botany Photo of the Day page and fill out the form in the upper right corner!
Plant Family / Families: Hydrangeaceae
Scientific Name and Author: Hydrangea aspera subsp. aspera 'Macrophylla'
Institution: UBC Botanical Garden
Accession Number: 016533-0104-1978
Name Location: Vancouver, British Columbia, Canada
Douglas Justice took today's Botany Photo of the Day and wrote the accompanying entry as well.
Hydrangeas are popular garden subjects, and the genus Hydrangea has been written about extensively. At least three popular volumes have appeared in the last few years, and the quality of writing and images in those books is impressive compared with what I had to put up with early in my horticultural career. Thankfully, modern hydrangea books take pains to discuss both the wild species and the cultivars (of which there are hundreds). Our collection of hydrangeas at UBC runs to about 20 wild taxa (species, subspecies, varieties, etc.)—most of them derived from Japan, China, and Taiwan—and includes deciduous small and large shrubs (some nearly tree-like) along with deciduous and evergreen climbers.
Michael Dirr, the respected woody plant expert and author of numerous horticultural books, writes of Hydrangea aspera in his excellent Hydrangeas for American Gardens (Timber Press, 2004): "All taxa umbrellaed by this species have large fuzzy leaves and stems, lacecap inflorescences, typically blue or purple in the central fertile flowers, with an outer ring of white to lilac-pink showy sepals. Large, knobbily rounded bud clusters foreshadow the flowers. Depending on one's aesthetic bent, the bud clusters are somewhat attractive to rather scary". Indeed.
Hydrangea aspera is native to an enormously wide geographical range, from the western Himalayas through Indo-China to Malesia and east to central and western China and Taiwan. Plants vary considerably both morphologically and with respect to cold-hardiness and heat tolerance, which shouldn't be surprising given that the species is found in both temperate and tropical habitats. The ability of plants to absorb aluminium—and to thereby colour their flowers blue—is also evidently variable. I've read that the flowers of H. aspera are unaffected by soil pH, but my own experience with the species (the cultivar in today's Photo of the Day, in particular) suggests that regular springtime applications of aluminium sulphate effectively cause the fertile flowers to appear bright blue when fully open. They are normally pink, mauve, or lilac-purple in unamended acid soil.
Posted by Eric La Fountaine at July 15, 2009 7:00 AM
Read recent comments on all BPotD Entries
Comments
Posted by: Annie Morgan at July 15, 2009 8:16 AM
Pretty! But for me, I will stick to the deep cobalt blue mop-head hydrangeas.
Posted by: mike at July 15, 2009 9:36 AM
How interesting! I was always told that you use aluminum sulfate (American spelling) to acidify the soil, and the extra acid turns the flowers blue (as if the flowers are a little pH strip). I use it for increasing the acidity of the soil for my blueberries, too.
But it is really the aluminum that is working the magic on the hydrangeas! That is good to know.
I will note that any aluminum sulfate you scatter around the base of a large hydrangea bush is not necessarily spread evenly throughout the bush.
I have a large bush and it is difficult to spread the aluminum sulfate really evenly. When the flowers bloom, some are deep blue, some are deep violet, some purple, some pure pink, on different sides of the plant. It is easy to see where I scattered more or less aluminum sulfate and where I might have missed a spot.
Posted by: Katherine at July 15, 2009 10:46 AM
I've had them here in West Linn for about 10 years. They are very strange and wonderful & kids love the fuzzy leaves. Leaves on mine this year are 14" long.
http://s243.photobucket.com/albums/ff91/badger545/Hydrangea/?albumview=slideshow
Posted by: JoLee at July 15, 2009 10:58 AM
(JoLee, you posted a link to a password-protected gallery)
So glad you posted a bud shot! I find this species to be overused to the point of irrelevance but I know my opinion on the plant is in the decided minority.
This is a popular plant here in San Francisco and every so often some enterprising criminal goes through a neighborhood cutting all the nice hydrangea heads and then selling them to the floral wholesalers at our Flower Market.
I also learned something RE: Aluminium. I also thought the blue was from the acidifying treatment and never connected the Al to the blue color.
Posted by: Eric in SF at July 15, 2009 1:10 PM
After looking at the picture, I misread deciduous for delicious.
Posted by: Meg Bernstein at July 15, 2009 1:27 PM
Its not the aluminium part it's the sulphuric acid produced when the aluminium salt hydrolyses
Posted by: Old Ari at July 15, 2009 2:55 PM
i dearly love hydrangeas all sizes
all colors just a favorite
daves garden has a nice little film
on planting hydrangeas in the garden
the close up is very scary indeed
thank you
Posted by: elizabeth a airhart at July 15, 2009 3:46 PM
I have often wondered about the mechanism behind the varying flower color in Hydrangeas. The blue-pink-red color spectrum in plants is typically (always?) generated by anthocyanin pigments. From my understanding, some of these may absorb light differently at different pH levels. So in Hydrangeas, it may be a *lack* of an ability to regulate internal pH that causes the flowers to change color depending on the soil pH. Still don't have a clear answer for this after speaking with numerous well-informed botanists. Of course, I haven't bothered to search the literature either!
Posted by: Cody at July 16, 2009 10:14 PM
I'm glad I looked long at this lovely photo, before reading the description and comments. It's interesting that some people find this "scary" -- I find it lovely and luscious! And the most wonderful colours, too.
Different strokes / à chacun son goût !
Posted by: Mary Ann, in Toronto at July 17, 2009 2:10 PM
Please share your comments about the photograph(s) and accompanying write-up. Telling a story about the subject of the photograph(s) is also much appreciated! If you have a gardening question, the best place to ask is on the UBC Botanical Garden Forums. Thank you!
Post a comment
XML Feeds: Atom | RSS 2.0 | RSS 1.0 | What is RSS? | RSS Tools
Botany Photo of the Day and all associated images are licensed under a Creative Commons License except when otherwise specified in the accompanying written entry.
About Botany Photo of the Day | Submit Your Photos via Flickr | Submit Your Photos via UBCBG's Discussion Forums
Botany Photo of the Day is a project of the UBC Botanical Garden and Centre for Plant Research, located in Vancouver, British Columbia Canada. UBC BGCPR is a department of the Faculty of Land and Food Systems within The University of British Columbia.
I've never seen a hydrangea plant in bud! Interesting how they get those rather virulent blue flowers seen in the florist shops.