Weird Plant Wednesday!

Inspired by Linda’s Euphorbia quiz last week – here’s another:

Euphorbia tirucalli ‘Firesticks’ in the Hahn Horticulture Garden at Virginia Tech (right before we dug it up due to impending frost). Am hoping for a "comment of approval" from Hap (Mister Cactus Jungle) on this nice specimen…not bad for Zone 6a!

Same funky little leaflets/antennae… just like Linda’s Euphorbia lactea ‘Cristata’

GP factoid: also known as "milkbush," the latex sap contains terpenoids – it apparently has potential as an energy source or "hydrocarbon plant."

Phosphate toxicity and iron deficiency

Bert’s post yesterday reminded me of some work one of my graduate students did about 10 years ago.  We were curious to see whether a transplant fertilizer containing phosphate was correlated with foliar iron deficiency, which is visualized as interveinal chlorosis:

 What Scott did was to plant 10 rhododendrons per treatment into pots containing containing a name brand azalea, camellia and rhododendron food (5-5-3) at 0, 0.5, 1.0, and 2.0 times the recommended amount. Here are some of the results of that study:

Total number of chlorotic plants

Total foliar iron vs. fertilizer treatment

Chlorosis as a result of phosphate fertilizer. 1= Normal (green leaves), 2= Light chlorosis in young leaves, 3= Moderate chlorosis, 4= Severe chlorosis, young leaves white

 For gardeners, the take home message might be that the control plants – those without any transplant fertilizer added – did the best. Don’t add phosphate to your landscape and garden soils unless you have a verified deficiency.  And only a soil test will tell you this conclusively.

You can’t fly by the seat of your pants on this one, folks.