Hydrangeaceae

Question 1

Key features:

Answer 1

• flowers as panicle, mopheads (rounded corymb), lacecaps (flat corymb)
• flower colors cream to pink to red to blue to purple
• leaves opposite, simple, w a serrated edge

Question 2

How does the change in flower color in big leaf hydrangea (hydrangea macrophylla) occur?

Answer 2

Soil pH levels!
Acidic soils = blue flowers
Neutral = cream flowers
Alkaline soils = pink and purple flowers
Change results from a color change of the flower pigments which occurs in the presence of aluminum ions that are more readily taken up in lower pH soils

Question 3

No hydrangeacea are native to MN, but St. Paul is at epicenter of hydrangeaceae. Explain.

Answer 3

Introduction of Endless Summer by Bailey nurseries in St. Paul revolutionized market. It flowered on new wood instead of old wood that would not survive the winter in cold climates.

Question 4

Which of hydrangeae species is the most hardy?

Answer 4

Panicle hydrangea (Hydrangea paniculata)

Question 5

Research at U of M has revealed members of which hydrangea species are hardier than their natural range would suggest?

Answer 5

Oak leaf hydrangea (Hydrangea quercifolia)

Question 6

Leaves from which hydrangeaceae plant genus contain a compound that can serve as a soap substitute?

Answer 6

Hydrangea philadelphus (Minnesota snowflake)

Question 7

What is a leaf miner? What does it do?

Answer 7

Larval form of insect that feeds on parenchyma layer of the leaf, as it travels through the leaf, it’s tunnels get wider.

Question 8

Biggest limitations in the landscape?

Answer 8

Cold hardiness.