Shade Trees of the Arboretum Tour Map

Here is a map of the shade trees we covered on Saturday August 4th. 

Keep an Eye Out for Summer Limb Drop

As the afternoons here get hotter and more humid it is the well irrigated trees that can become a threat. Summer limb drop affects trees like the Floss silk tree, The Italian stone pine, and other susceptible varieties. Here is a news interview I did on the subject several years ago after some children were injured by a falling pine tree :

2010 Gardens of California Lecture, Enjoy!

Beating the Heat Lecture: How to Protect Your Plants in Record Temps

BEATING THE HEAT

·      July 6^th -119 degrees F for over an hour here.
Many Plants Scorched.
In the following days trees, shrubs and woody plants start to defoliate.

The Physiology of Heat Damage

·         PWP -mostly a problem with herbaceous plants.

·         Chloroplast damage -sets off a chain reaction in the plant.

o   Increased production of protective proteins

o   Increased production of abscission hormones.

o   Increased production of damaging peroxides.

·         Leaf drop

·         Fruit drop

·         Flower drop

·         Twig drop

·         Leaf scorch

·         Trunk and branch scorch (citrus and avocados)

·         Limb drop in susceptible trees.

What to Do After

·         Mulch

·         Increase irrigation frequency (but do not overirrigate)

·         Do not fertilize

·         Do not overwater

What if More Heat is on the Way?

·         Anti-transpirants?

o   Work by either plugging up the stomata or causing it to close.

o   Can cause overheating, decrease transpiration.

o   Work best in frost situations

·         Misters

o   Are expensive

o   Can cause fungal infestations

o   Require installation and $

o   Cheap barrel misters may be the best bet.

·         Shade-cloth

o   Can injure plants if just ‘draped’ on.

o   Should be installed as a permanent structure.

o   Need to choose right % for the plant.

o   Do not prevent all heat damage.

·         Kaolin

o   Sprays on

o   Helps control some insects as well

o   Irrigation washes it off.

o   Looks terrible.

·         Modify Irrigation

o   Check Evapotranspiration Index

o   Water according to current ET number.

§  Make sure you do irrigation measurement before you do this.

o   Use coffee cups and turn irrigation on for 10 minutes, measure depth in inches.

·         Plant Choices

o   Plants with blue-green coating (glaucous) do well.

o   Plants from South Africa and Madagascar do well.

o   Plants form the Southwest, South and Central America (not all).

o   Many (not all) Australian plants.

o   Plants from temperate areas do not usually do well.

·         Landscape Choices

o   Remember to put heat and sun resistant plants near walls and walks.

o   Go with climate appropriate plants.

o   Build shade structures.

o   Consider a mist system (for you, not the plants).

Links:

Scorch, Sunburn, and Heat Stress

Plant tolerance to high temperature in a changing environment: scientific fundamentals and production of heat stress-tolerant crops

When it is too hot for photosynthesis: heat-induced instability of photosynthesis in relation to respiratory burst, cell permeability changes and H2O2 formation

Leaf scorch | The Morton Arboretum

Sunburnt plants 'myth' is debunked - Telegraph

leaf-scorch.pdf

Extension Service | Leaf Scorch

8445.pdf

Bacterial Scorch of Trees

Leaf scorch | The Morton Arboretum

Bacterial Leaf Scorch

Homemade Whitewash for Trees

Whitewashing an Avocado Tree

UC IPM: UC Management Guidelines for Sunburn on Avocado

Surround WP (25 Lb) - GrowOrganic.com

Reserach-Summary_Cochran-Dissertation-MBI.pdf

How to prune heat damaged foliage

Impacts of Kaolin and Pinoline foliar application on growth, yield and water use efficiency of tomato (Solanum lycopersicum L.) grown under water deficit: A comparative study

https://cimis.water.ca.gov/

Madagascar Exhibit, Cactus and Succulent Garden are in Fine Form Right Now

One nice aspect of our collection in the summer is that some of the most heavily blooming plants are located near the entrance, making it not a dire hike to see them. Here are some pictures I took today of sections showing bloom that are fairly close to where you come in.

Crazy blooming plants in the Cactus and Succulent Garden. The red flowers are California native Chuparosa (Justicia californica)

Hummingbird navigating through a 'Sunset' Tecoma. 

A gazebo located at the north edge of the Event Lawn. 

The entrance to the Cactus and Succulent Garden. 

Yellow flowering Uncarina decaryi and tall Alluaudia procera in the Madagascar exhibit.  

More Madagascar Exhibit loveliness. 

Closeup of Uncarina decaryi. 

Flowering Crepe myrtle tree on the walk just north of the entrance. 

Here's a map to most of the above locations: Click here. 

Pests Lecture

Thanks everybody who came to the plant information class on insect and other pests.
Here's a page that goes over the orders that we covered in class and more. 
Also, the mammal pests we covered were:
Rats, Raccoons, Bears, Deer.
We also covered: Peacocks, Sapsuckers, Woodpeckers, Snails and Slugs, and Arachnids like ticks and spiders.
And finally,

Having bad luck with your houseplants?
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7 Coolest Places at the Arboretum.

OK, when it's 117 it's too hot to go anywhere, however when the temps get back down to reasonable (max 102), here's some places to check out here and stay cool. 

Tower of Jewels Is Glorious Right Now

What better way to keep the Hawaii eruptions in mind than to enjoy the splendor that is one of the Canary Islands most striking flowering plants (and the Canary Islands has many striking flowering plants) -the 'Tower of Jewels' (Echium wildpretii).  E. wildpretii can be found on the clinkery lava plains of mount Teide; a still active volcano that is responsible for forming the island of Tenerife. 

Below is a picture of Echium before it bloomed. Notice the silvery, linear pointed leaves. The silver sheen is created by hairs that reflect the heat coming off of the black, heat radiating lava that is common around the volcano. Here is a picture of the plant growing in its native habitat. 

The plant in bloom looks quite similar (except for the pink blooms) to the Silversword (Argyroziphium sandwicense), an unrelated plant that grows on the Hawaiian island of Maui.  This is a phenomenon known as convergent evolution. It is not known if the Silversword attracts hummingbirds. 

Echium wildpretii does attract hummingbirds (and bees), so scroll down and enjoy the show. These E. wildpretii are located next to the south parking lot gate inside the Arboretum. Here's a map. 

Awesome Botany Video -Botanist Inadvertently Finds Rare Plant -Via Twitter

Out in the Garden, April 24th 2018

It's still glorious out there. The Crescent garden's wildflower display is showing no signs of letting up. 

Crescent garden. 

 The view of the San Gabriel mountains from the event lawn is peppered with colorful plants in full bloom.

View from the event lawn. 

 Almost everywhere something's blooming, like this flowering almond tree near the west end of the Baldwin lagoon.

Flowering almond in a bed of Canna 'Tropicanna'

More Crescent wildflower goodness. 

Monkey flowers and Phacelia in the Crescent garden. 

Romanesco broccoli in the Crescent garden. 

A yellow faced bumble bee in the Crescent garden. 

Veltheimia in the South African section.  

Apricot Tabebuia Blooms Twice

Something I don't think I've seen before; our Apricot Tabebuias have bloomed twice. The first picture is of one the Apricot Tabebuias located on the road near the Tropical greenhouse taken February 14th. Then it went through its normal cycle and finally lost its blooms about a month later. 

Then, instead of re-leafing, it bloomed again! Below is a picture of the same Apricot Tabebuia taken today (almost 2 1/2 months later!). It has returned to full bloom instead of re-leafing, like it usually does, after the first bloom. 

Is this normal? Well I haven't seen it before, however that could be because I haven't noticed it before. This has been an early, and apparently long lasting spring. 

April Heat Brings Out the Blooms

Considering how meager our rainfall has  been (only 7" here so far), the recent cool weather has allowed those plants that are irrigated to develop lots of flower buds, and now the heat is popping those buds like crazy. A walk around the Crescent garden and the Meadowbrook section is like stepping into an impressionist painting. 

Crescent garden California poppies. 

Crescent garden California poppies. 

Left:  Snowball viburnum. Center and Right: the Kallam garden. 

The meadowbrook brook. 

Crescent garden California poppies. 

More Crescent garden California poppies. 

Crescent garden annual wildflower display (Leigh Adams on the left there). 

Crescent garden wildflower display. 

The Meadowbrook section brook. 

Crescent garden California poppies. 

Water Saving Plants for Shade

Clivia 

These beautiful dark green flowered plants grow no more than 2 feet tall and will bloom in bright shade with little more than once every two weeks watering once established (more if planted in a brighter area). 

Clivia nobilis

Clivia miniata

Clivia miniata

 Aspidistra elatior 'Cast Iron Plant'

This plant comes from a tough family, including Nolina and Sansaveria. In fact it is so tough and hardy it has its own song, this plant needs only a glance or two to stay healthy, and as far as water -once every two weeks or less after it's been established (about 2 years).

Aspidistra elatior

 Abutilon 'Chinese lantern'

Hardy and colorful member of the hibiscus family; best trained as an espaliered vine in shade. Water it once every one to two weeks once its established. Blooms in bright shade. 

 Aeonium 'Schwarzkopf' The 'Black headed' Aeonium

A succulent that doesn't mind some shade, its leaves are purple black with green new growth. In sun it will shrink to what looks like small drumsticks, but in shade it should remain lush looking throughout the year.,

 Asparagus meyeri 'Foxtail asparagus'

More kempt and controlled than common springeri ornamental asparagus; meyeri will do well in moderate to bright shade and need watering only once a week to week and a half. Keep vigilant however, as this one can easily grow out of bounds. 

 It lends itself to whimsy as well.

Acanthus molle  'Grecian pattern plant' 

Acanthus molle's common name refers to its ancient use as an inspiration for the decorations on greek marble columns. Like the long lasting columns the plant is tough and can thrive in relatively dark areas. It does, however, die back every summer, only to come back again in the spring. This 'resurrection' was the reason it was considered sacred by the greeks. The sacred and beautiful spike-like flowers however, do have a somewhat 'unholy' smell to some people -and remind the author of semi-spoiled milk.

 Raphis excelsa 'the Lady palm'

Not only a lady but can take an occasional dry week or two once established, not as drought tolerant as others on this list -if too deprived it will lose leaves, but sowly. 

 Amaryllis belladonna the 'Naked Lady'

Bulbs that come up every summer in the shade when nothing else is blooming -Amaryllis require once a week watering when blooming and much less when not in bloom. Does best if it gets a hint of direct sun (about 2-3 hours).

Amaryllis belladonna

Amaryllis belladonna

Spider lily (Lycoris sp.)

Lycoris sp. 

Spider lilies blooming in front of a Spider. 

Creeping fig (Ficus pumila)
This is one of the few vines that do ok in shade. Remember to cut this one back every 5 years or so; if you don't it could develop robust flowering shoots that do not cling to the wall and take up valuable space.

Ficus pumila

Snake plants (Sanseveria sp.)

Tough plants related to Aspidistra, they have the nickname 'Bachelor Plant' because they are so tough even the negligent can keep them as houseplants. They are also excellent outdoor plants and can tolerate a good amount of shade. 

Heavenly Bamboo (Nandina sp.)

Normally planted in sunny areas, it will survive in bright shaded areas as well with watering only once every one to two weeks. 

Nandina sp. 

Nandina sp. 

Natal Plum (Carissa sp.)

This South African native shrub actually tolerates light shade and can be used as a hedge in bright shady areas. Once it's established it needs watering every two to four weeks in a shady area. 

Carissa sp. 

Variegated dwarf Carissa

Berberis (Mahonia) repens

This low growing, creeping ground cover can go a month without water once established. Great companion for native oaks. 

Berberis (Mahonia) repens

Western Redbud (Cercis occidentalis)

The Western redbud is an understory tree that grows natively in the Sierra Nevadas and other western mountains. It will bloom in bright, filtered shade or with several hours of direct sunlight. Once established (about two years) it can go 2-4 weeks between waterings. 

Redbud