L.A. County Arboretum & Botanic Garden Plant Info

Browse Our Magnolia Collection -Beta Testers Wanted

2012-01-25T17:08:00.000-08:00

I've published a Google map of our Magnolia collection. Each one of the blue icons is a Magnolia in our collection, just click on it and you'll get a short description and history of each plant. It's cool, but the coolest thing is that you can load this map up on your Google Maps app on you iPhone or your Android phone and use your GPS to find out what Magnolia you're looking at in the field. Try it out if you have one of the above and let me know how it works for you.

View Flowering Magnolias at the L. A. Arboretum in a larger map

Wild and Wooly

2012-01-21T16:50:00.000-08:00

When I started this job 14 years ago I'd get lots of stuff in the mail. Sometimes the packages would be dripping strange fluids, emitting strange odors and containing strange life forms. These days with email and digital photography I'm mostly spared these surprises but there are still things that require a sample. The pest below is a good example of this. What you see is a citrus whitefly. Now 'citrus whitefly' is a term for any of three different species of whitefly that currently infest citrus trees.

Sample of citrus leaves with wooly whitefly infestation.

The sample you see on the left is a lemon tree that has been infested with citrus whitefly. Notice the fuzzy white patches. These patches are the reason I needed to see this sample. When this had been originally described to me it was described as a 'fungus'.

Now of the three whiteflies that infest citrus here this one appears to be the 'wooly whitefly'.

Now if you look closer (the lower two images were taken with a magnifier) you'll notice that the 'fungus' looks more like cotton and that there are what look like scale insects surrounding the fuzzy stuff. These 'scales' are actually the immature (nymphal) stages of the whitefly. These 'nymphs' will eventually cover themselves in a cottony tuft of wax fibers (the 'wool' in the pests common name) that the exude from their bodies. This wax serves to protect them from predators and it also repels water (that's why most contact insecticides will not control them very well).

Some methods of control that do work are:
1. Pruning the tree to increase air circulation.
2. Spraying horticultural oil solution on the tree. This has to be done during the cool time of year or else the oil spray will damage or kill the citrus tree's foliage.
3. Decreasing the amount of nitrogen that the tree receives. Instead of feeding three times a year feed just once. If you feed citrus too frequently their sap's concentration of nitrogen goes up. Since nitrogen is the limiting factor in the growth of the pests (they've got all the sugar they need for energy -what they need is nitrogen to form the proteins of their body tissues) if you over fertilize you're practically sending out an invitation to white flies and pests like them to infest your trees. Use organic fertilizers because their availability coincides with the availability of the natural predators that keep the white fly under control -in other words when its warm outside there are lots of predators to control the whiteflies so that is the ideal time you want fertilizer to be available to your citrus trees. Do not use fertilizers that are immediately available to the plant like ammonium nitrate and urea (found in commonly available water soluble fertilizers like 'Miracle-Gro').

For more information on control of this whitefly download this PDF:

January 17th out in the Arboretum

2012-01-18T14:36:00.000-08:00

Flowering stalks of the King palm (Archontophoenix cunninghamiana).

Tan, pom-pom like flowers of Acacia stenophylla blooming in the Australian section.

Acacia spectabilis, the 'Glory Wattle', earns its common name. Located in the Australian section.

Acacia merinthophora's distinct arangement of stems and phyllodes (leaf-like stems) gives it its common name: the Zig zag wattle.

Back from Flu Bout; Class Rescheduled

2012-01-06T17:30:00.000-08:00

I'm back after a wicked bout with that seemed like the flu. For all of you who missed the class yesterday I'll be holding it next Wednesday, same time same channel (1:30 to 3:00 in my office). I'll be covering Spring bulbs, local fungus (in preparation for the rainy season which is not here just yet), and of course the best of 2012's plant information questions so far.

Here's a cool link; it's the UCR Avocado variety page. The trick is to select at least two varieties that are good for your climate zone and are A and B type Avocados respectively. Having both of these flowering types can help insure a steady and abundant supply of Avocados.

A Rant On Liquidambars

2011-12-28T16:45:00.001-08:00

Our recent breezy weather is bringing out lots of concern about the safety of trees planted next to houses. I recently had an inquiry regarding one tree that should never be planted near houses or any hard-scaping for that matter...and it's not a Ficus.

Liquidambarstyraciflua is a tree native to parts of the Southeast United States, Mexico andparts of Central America. It’s called a ‘Sweet Gum’ because Native Americanswould chew the tree’s resin like chewing gum. The tree is not at home here in dry SouthernCalifornia. Where it's native the precipitation averages 25-35 inches of rain ayear. The problem is that it is also a tree that has evolved to survive inrocky, infertile soil in its native range. This ability to ‘tough out’ those harsh conditionsmakes it appear to be the perfect tree for Southern California; nothing isfurther from the truth. With the dry winds and the infrequent precipitation Liquidambars here are constantly under water stress. They also have the propensity to developvery invasive and destructive roots. Butwait there’s more. Ever since 1998 when a new pest called the ‘glassy wingedsharpshooter’ was introduced to California Liquidambars have been infected witha disease called ‘scorch’. Firstappearing on Oleanders, this disease is a bacteria that plugs up the waterconducting tissues of the plants it infects and causes the shoots furthest from roots to dry out so fast they literally ‘scorch’ where they stand. This has gotten so bad in parts of Riversidecounty that it causes the trees to die back to almost 2/3 of their former height,causing them to look disfigured and leading to their removal for aestheticreasons.

Now also consider that the chances of damage from the wind toppling Liquidambar trees is probably not as great as the chances that thetrees roots will damage some structure that the tree is within 10-25 feet of.

So all this leads me to my final opinion on yours, and every other Liquidambartree growing in Southern California. Unless your tree is at least 25 feet awayfrom any structure it can damage with its invasive roots, and is surroundedby a lawn (which is the only way it’s going to get sufficient water to remainhealthy and tolerate the effects of the scorch disease) I would remove thetrees and plant something else.

Links:

Here's an article I wrote two years ago about Liquidambars

Australian Garden Expert Don Burke's List of Trees to Avoid; This Advice Good for Southern California Too

Scorch damage on a Liquidambar leaf

Aquamog Returns to the Arboretum

2011-12-21T21:28:00.000-08:00

This whimsical machine is going to clean out all the debris that the winds knocked into the Baldwin lagoon!

2011-12-20T17:29:00.000-08:00

The L.A. County Department of Parks & Recreation tree crew guide the large central trunk of a hazerdous tree being removed from behind the Arboretum gift shop.

2011-12-17T17:31:00.000-08:00

Work continues on cleaning up the wind mess here at the Arboretum. In this picture tree crews are removing toppled limbs from a large Ficus tree located on the south part of Tallac Knoll.

Should She Remove A Wind-bent Fan Palm?

2011-12-13T17:23:00.000-08:00

Spent most of the day working on a new GIS system that will allow us to map the 326 lost trees in less than a weeks time -a real improvement over the 5 year mapping cycle that is the norm for our 14,000+ collection. Tomorrow the system gets a field check.

I had a call today from a Pasadena resident who noticed after the wind storm that her neighbors tall Mexican fan palm has a noticeable lean of almost 45 degrees. This is not necessarily a death sentence, as evidenced by the existence of many 45 degree leaning palms on the Arboretum grounds. There was, sometime in the late 1880's a horrific windstorm that blasted the San Gabriel valley, maybe the Arboretum's leaning palms were the result of this storm? At any rate since palms are so resilient you might say what doesn't kill them makes them stronger. Since she related that if the palm failed there would be no great consequence I suggested she enjoy her per-quaky palm.

Queen Anne Cottage (pre-windstorm) showing leaning, but stable Mexican fan palms.

Nature and Beauty Don't Seem to Care About the Winds

2011-12-11T16:39:00.000-08:00

Egret stands in small stream in Meadowbrook section.

It's Sunday here at the Arboretum and the windstorm chaos of a week ago almost seems a thing of the past; except for all the branches and debris. Walking through the Arboretum I'm amazed how nature continues its sublime production despite the blow it's both received and dealt.

Japanese maple blazes a brilliant autumn red while in the background Arboretum staffer Glen Klevdal cuts wind-felled branches in preparation for their removal.

2011-12-09T16:37:00.000-08:00

The progress being made here since the 'Mighty Wind' has been heartening. We have several tree crews from different county organizations working on the clean up including County Fire Department camps 2 and 9 and the L.A. County Dep. of Parks and Recreation's tree crew.

Starting to Get Back To Normal

2011-12-07T17:00:00.001-08:00

After days of slogging through the debris covered cataloging and evaluating trees with senior biologist Jim Henrich some normalcy has occurred; I was able to give my monthly plant information class hold a small holiday party for my volunteers. At first it didn't look like it would happen. The damage looked so great here that it was thought that the Arboretum would be closed for months. That is not the case now, thanks to the efforts of a lot of different people in the county. Today we had crews from trail maintenance, county fire, and several others chain-sawing downed trees, cleaning up debris, and chipping limbs. Add to that the support and calls to offer assistance, and the press coverage of what has happened here, I never thought I'd be so hopeful as I am now...incredible progress is being made.

County Fire Camp 2 and 9 crews helping with the cleanup here at the Arboretum.

2011-12-05T17:12:00.001-08:00

Richard Schulhof and Tim Phillips Describing Wind Damage at the Arboretum

This is a link to a video interview of Arboretum director Richard Schulhof and Tim Phillips talking about the damage done by the hurricane force winds here. It was done by the Web Newspaper 'Arcadia's Best'. What's really interesting is that Tim Phillips has had experience as a supervisor at a botanic garden in the Caribbean that was struck by a hurricane; hear how he compares the damage between the that experience and Friday morning's devastating winds here.

The WInds

2011-12-01T14:35:00.001-08:00

Last nights winds sounded like a jet engine parked next door and left on full power. I stayed inside my place, but when I did look out all could see were all the trees in the neighborhood doing a crazy, insane dance; diving and bending at angles I didn't think possible for any living thing. I live a few blocks from the Arboretum so I was not looking forward to going to work.

I walked up Baldwin to the Arboretum and saw branches and uprooted trees everywhere, and then I arrived at the Arboretum.

I was heartbroken by the shear magnitude of the devastation; hundreds of trees damaged or lost. I took some pictures so you can get an idea of how much of a hit the Arboretum has taken. Now I know that some of these trees might recover, and that these kind of winds are a normal, if not a very frequent, occurrence here (this noted by the low number of native oaks we lost); but it's still sad to think some old friends out there in the Arboretum are lost forever. Enough blog writing, time to help my coworkers clear some debris.

Will This Be the Last Fall Color Blast?

2011-11-30T16:56:00.001-08:00

Winds of 60 to 70 miles per hour are predicted tonight for the L.A. Basin and outlying areas; will these winds visit the normally wind-sheltered area underneath the San Gabriel mountains where the L.A. County Arboretum & Botanic Garden is located? Stay tuned...until then here are some pictures I took just today and yesterday; they may be the last pictures of fall color here before the wind blows all the leaves off of the trees. BTW, check out the huge flowering Dahlia imperialis located in the Garden for All Seasons
11/30/2011

11/29/2009

For more on Fall color around the state, check out http://www.californiafallcolor.com

More Fall Color Shots

2011-11-29T17:05:00.001-08:00

Out and about on the grounds and the show goes on; the Fall color is still amazing!

By The L.A. River

2011-11-23T16:57:00.001-08:00

Went down to the river today to look at plants for a filmmaker/artist doing a piece on the origins of the plants that find there way into the river bed and found some interesting stuff. One of the more interesting sights were a group of egg-like mushrooms growing in a sandbar right there in the river. I took them back to the office and identified them as Phallus impudicus, the Stinkhorn mushroom. This mushroom usually grows on under-composted wood mulch but here it was growing on the roots of a recently killed Arundo donax plants. Here's a video of Phallus impudicus fruiting in time-lapse. ( Warning: Not for the Faint of Heart or Easily Disgusted ).

I'll go over some of the other interesting stuff in my next post.

Another Fall Color Report

2011-11-22T14:49:00.000-08:00

More Fall Color

2011-11-19T12:38:00.000-08:00

For kids with ADHD, regular 'green time' is linked to milder symptoms

2011-11-15T11:21:00.000-08:00

For kids with ADHD, regular 'green time' is linked to milder symptoms

If you've ever noticed your kids seem to behave better when you take them to the Arboretum, well here's a scientific study that backs you up!

Fall Color Report 11/12/2011

2011-11-12T12:53:00.000-08:00

Album with map locations here: https://picasaweb.google.com/botaknee/FallColorReport11122011?authuser=0&feat=directlink

More Fall Color

2011-11-09T17:11:00.000-08:00

Arboretum Fall Color 11-9-2011

This album includes a map that shows the locations of the subject trees.

Looks Like Fall Color is Ramping Up

2011-11-08T16:49:00.000-08:00

I was out on the grounds this last Sunday and the Fall color is starting to look good. Keep your fingers crossed that we don't have any hot, windy Santa Ana winds or heavy, driving rain. Here's some of the pix I took while I was out on the grounds:

Plants that Peacocks Pass

2011-11-04T16:41:00.000-07:00

Every two months here in peacock graced (or infested depending on your opinion ) Arcadia I get inquiries about what plants they will not eat. First off, peacocks will dig up newly planted small container plants just to get at the grubs and insects that the newly transplanted plant's injured roots attract; second peacocks like the new foliage of plants they may not necessarily feed on once the foliage has matures. The best thing to do with flowers is to establish them in area that has been surrounded by bird netting. If you can't do that then try using a motion detecting scarecrow to do the job; but be careful, I once almost gave a UPS delivery man a heart attack when my motion detecting scarecrow went off without warning and scared the daylights out of him.
Here is a list that has been compiled over time here at the Arboretum of plants that are resistant to peacocks.
Agapanthus
Azalea
Baby’s Breath
Bee Balm
Bird of Paradise
Blazing Star Liatris
Bougainvillea
Butterfly Plant
Cactus
Camellia
Cannas
Clivia
Columbine
Coneflower
Ferns
Fuchsia
Gaillardia
Gardenia
Geranium
Giant Columbine
Gladiola
Gloriosa Daisy
Hen & Chicken
Hibiscus
Hardy Lavender
Hostas
Iceland Poppies
Iris
Ivy
Lantana
Lavender
Marigold
Mint
Mum
Oleander
Painted Daisy
Periwinkle
Peonies
Phlox
Pink Lady
Plumbago
Poinsettia
Pyracantha
Rhododendron
Rose
Shasta Daisy
Snap Dragon
Sunburst Coreopsis
Weigela

Super Soperific Sapote

2011-11-03T15:03:00.000-07:00

A volunteer brought in a green fruit he found on the grounds today and wanted to know what it was; turns out it's citrus family member white sapote, Casimiroa edulis. I did a little research on the fruit and found that it's considered soporific, in other words, a sedative; surprisingly one of the ingredients responsible for this effect is a compound that mimics histamine, the chemical messenger that tells our body to swell up in response to bee stings and pollen.

California Rare Fruit Grower's white sapote page :

http://www.crfg.org/pubs/ff/whitesapote.html

Purdue Horticulture Department's white sapote page:

http://www.hort.purdue.edu/newcrop/morton/white_sapote.html