Monday, August 11, 2014

Week Seven

Although we did a wealth of different activities this week, I'm going to hone in on our work this Friday in Kew's aquatics garden.  Now that the internship is more than halfway over (where has the time gone?), I wanted to make sure that I wrote about this interesting spot just in case we don't have the chance to work in there again this summer.  Although I mentioned a bit about this in my second week's post, I think it would be worthwhile to go into a bit more detail about this section of the gardens.

All about the aquatics garden

A quick history
Water lily surrounded by duckweed (Lemna)
Although Kew has had aquatic displays in and surrounding man-made, in-ground lakes and ponds since the beginning, it wasn't until the directorship of Sir William Hooker that tanks were constructed to display hardy aquatic plants (Desmond, 148).  A somewhat small tank was installed near the northern side of the herbaceous beds in 1841, and was used for that purpose until at least 1873.  In 1879, Sir William's son and successor Sir Joseph Hooker replaced the tank with a larger brick tank that spanned 80 feet (Desmond, 211).

The improved tank was replaced in 1909 by a large central tank flanked by two rectangular tanks to the sides and four smaller ones on the corners (Desmond, 351).  According to some material that Shelley gave us earlier in the internship, the "new" aquatic garden was originally known as "White City" because it was made of bright, new concrete.  Needless to say, the appearance is quite different today.

Aquatics garden prior to weeding
White City had only cost £600 to build.  When the surrounding pavement was relaid in 2002, the improvements cost £5,000.  That's more than eight times the cost of the original construction!  This design is still in use today, although the central tank was raised up to give more depth for larger lilies in 1935 (Desmond, 353).

Much of the original plumbing is still in use, which means that its prone to leaks and breaks.  Five weeks ago, Shelley discovered that a pipe no longer filled one of the long tanks with water.  She immediately shut the tap off (because the water had to be going somewhere) and called maintenance.  The problem with fixing this system, as is true with all of Kew's irrigation, is that it is difficult finding the parts for such old plumbing.

Keeping it clean
Weeding is an important part of any garden maintenance plan.  For some reason, before I started at Kew I figured that water gardens would require less weeding than traditional beds.  Boy, was I wrong.  Duckweed (Lemna) and blanket weed need to be removed regularly to keep the desirable plants from being overcrowded and to ensure the surface of the water remains a dark, reflective surface.

Daisy demonstrates how to remove
blanketweed algae with a rake
Kew tries to prevent blanket weed algae from forming by dyeing the water blue.  The idea is that this type of algae forms below the water surface.  If the water is darkened, this reduces the amount of sunlight the plants receive, which should reduce growth.  The practice is effective in combination with regular weeding.  Algae can be removed by scooping it out of the tank with a rake or by simply harvesting it by hand.  Usually blanket weed will come up in a huge, continuous mass.  It actually resembles a blanket, which is why it's called blanket weed.

Duckweed is a whole different problem altogether.  It's brought into the tanks on the feet of aquatic birds (thus the common name "duckweed"), plant containers, and even tools.  The water dyeing trick doesn't work on Lemna because it naturally grows along the surface of the water.  That's why making the water dark doesn't slow growth.  Unlike blanket weed, duckweed doesn't stay in one big mass when you try to remove it.  Although it may look like a big, unbroken sheet from above, it's actually a collection of thousands upon thousands of itty bitty plants.  Try to scoop it out with a rake and you'll see all the pieces scatter away.  That's why we use nets to remove Lemna, but even then it's just impossible to get it all.

Bugging out
In addition to weeding, we also do pest control.  Although the water lilies were relatively healthy last time we worked in this area, they've developed a pest problem since then.  The water lily leaf beetle lays its eggs on the foliage.  When the eggs hatch, small black larvae emerge and begin chomping voraciously on the leaves.  They cut tunnels through the pads, which stress the plants out and look very unattractive.  It also doesn't help that the adults feed on the plants too.

Damage caused by water lily beetle larvae
There's not much that we can do to control the pests beyond simply spraying the eggs, larvae, and adults off of the plants with a water hose.  However, removing aquatic pests on aquatic plants with a spray of water into a tank of water isn't super effective.  Most of what we do is remove the damaged foliage so that the plants look cleaner and some of the pests are removed with the green waste.

This is nothing new
The information packet Shelley gave us for the aquatic garden contained a page from the Kew Guild Journal from 1909 to 1910.  The author was describing the new plans for the aquatic garden, and wrote about Sir Joseph Hooker's older garden.  "The old tank in the herbaceous ground, of which some of our readers will remain very muddy memories appertaining to its annual clean out, has been cleared away."  Although Daisy and I are only at Kew for a short time, it feels really special to share this murky experience with gardeners across Kew's past and into the future.

An intern's perspective
I think everyone enjoys working in the aquatic garden at this time of year.  When it's hot, humid, and sunny outside, this is a very cool activity.  Chasing after the Lemna is always a bit disappointing for me, because I really do want to get all of it out.  But that's impossible for reasons already stated.  The important thing is that the gardens look much better at the end of the day than they did at the beginning.

What else did we do this week?

We skipped edging the order beds on Monday, because the grass simply hadn't grown.  London's been in the grip of a drought since I arrived in June, and I guess the grass just couldn't handle it anymore.  This week much of the grass when from a dry green to a crunchy brown.  So there was no point in edging because nothing had grown.

Aquatics garden after weeding
Our crew spent a day and a half cutting and cleaning up the long grass along the boundary wall between the order beds and Kew Road.  This was intensely interesting, but I think I'm going to save what I was going to write about it for next week's post.  I don't want to overwhelm folks with too much information, and I'd also like a bit more time to observe how this difference affects the wildlife in our area.

Hitching my wagon to her star
Friday afternoon, Daisy was struck with a brilliant idea.  We've both been a bit distressed that we haven't been able to see much of the gardens, even though we've been working here for seven whole weeks.  It's hard to work up enough stamina for a romp through the 300+ acre property after a hard day of manual labor.

But Friday, Daisy proposed a fine solution.  Instead of walking through the gardens, she suggested that we hop on the Kew Explorer tram.  The tour guide was clear and informative, we saw loads of new things, and had a fun time!  I'd recommend the journey as a good way to start a visit to Kew.  It's only 40 minutes long, you get an idea of where everything is and of what you want to see.

Thanks for reading, and check back to read what happens next week in my internship with Kew.

If you have any questions, comments or suggestions, please feel welcome to leave a comment or send me an email.

To see more photos from this week, be sure to check out the album "Week Seven" on the Plante on Plants Facebook page.  "Likes", shares and comments are appreciated. 

This week's British treat is India's homemade white chocolate and pistachio cake.  Moist, smooth, and flavorful.  That girl knows how to bake!

India's tasty and delicious white chocolate pistachio cake.  Oh so good!

A nice, cool way to spend a Friday!  Photo by Daisy.

  • Desmond, Ray.  (2007).  The History of the Royal Botanic Gardens Kew (2nd Edition).  London: Kew Publishing, Royal Botanic Gardens, Kew.  177-179, 345-346.
  • The Plant List website
  • The Royal Botanic Gardens, Kew website and staff


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