This week we have one tropical, a native shrub and a bonus obscure native wildflower, plus a good hydrangea that should do well statewide.
Thunbergia grandiflora – Sky Vine or Blue Trumpet vine is a tropical vine for mid-summer into fall flowering. It is related to the orange and yellow black-eyed Susan vine or clock vine, Thunbergia alata.
The flowers are much larger on the Sky Vine
than on the Black-eyed Susan vine and a beautiful shade of lavender blue with a yellow center. It blooms best in full sun to partial shade. Native to India, it is an evergreen vine where it is hardy, but could overwinter in a greenhouse or indoors.
Buttonbush – Cephalanthus occidentalis
is a native deciduous shrub for full sun to partial shade. In the wild you will find it growing in moist, boggy situations, but it is actually fairly well-adapted to a wide range of soils provided it gets water when it is dry.
It has a large native range, growing wild from Florida through Canada. It blooms on the new growth, so any needed pruning can be done before growth kicks in, in the spring. Beginning in early to mid-summer small fragrant white balls of blooms open. They look somewhat like little meteors to me. The flowers are a favorite of butterflies, bees and hummingbirds. After bloom, the flowers heads mature into a hard red or pinkish ball
which can persist into the winter turning dark with age.
Hydrangea serrata – Mountain hydrangea –
It is a hardier plant than the bigleaf hydrangea. Many of you guessed lacecap hydrangea, and lacecap is a flower form,
differing from the mounded mophead type of blooms.
The flowers on Hydrangea serrata do have a lacecap form of a bloom
– with clusters of small florets in the center with larger showier flowers on the outside of the bloom. The average mountain hydrangea does set its flowers on the old wood, similar to big leaf (Hydrangea macrophylla) and oakleaf hydrangeas (H. quercifolia), but the one in the picture is a reblooming Hydrangea serrata called Tuff Stuff.
It is a newer reblooming variety so it will bloom in early summer on the old wood and again in later summer on the new wood, similar to Endless Summer big leaf hydrangea. It only grows 2- 3 feet tall and wide and it should not suffer as much winter damage as a big leaf hydrangea, so would be a better option than bigleaf hydrangea for the northern tier of the state, however it should do well statewide. It does best with morning sun and afternoon shade in well-drained soil with ample moisture. The flower color will vary based on soil pH—pink in more alkaline soil and blue in more acidic soils.
Bonus plant
A friend emailed these pictures into Facebook for identification.
I had never seen it before and it took me a bit of time to research it, and I came up with Streptanthus obtusifolius. Ann came up with Streptanthus squamiformis. On further research I have seen it as Streptanthus maculatus spp. obtusifolius.
Common names include Clasping jewelflower and Arkansas Twistflower and Clasping Twistflower.
It is in the Brassica family, along with cabbage and mustard.
From the Arkansas Endemic Biota report: Order Brassicales Family Brassicaceae Streptanthus maculatus Hook ssp. obtusifolius (Hook.) Rollins 1959 – Clasping Twistflower This twistflower is added to the Arkansas list of endemic plants. It is known from Faulkner, Garland, Hot Spring, Howard, Montgomery, Polk, Pulaski, and Saline counties. Streptanthus obtusifolius was formerly (Kartesz 1994) considered within the range of variability for S. maculatus but Kartesz and Meacham (1999) subsequently recognized it as a subspecies.
So now we know!