Monday, September 21, 2015

White Flowers of Fall

Late summer and early fall is when the asters and goldenrods dominate the the landscape.  These are beautiful plants and provide tons of food for pollinators, but I was trying to think of other native plants that were actively blooming at this time.  I was especially interested in plants that are not too tall, ones that could be used near the front of a garden border.  One beautiful native that comes in late summer is Blue Mistflower (Conoclinium coelestinum), but it seems to be winding down now in my gardens.  I had hoped to have some sneezeweed (Helenium autumnale), but this is the first year for the plants and something ate off the tops (deer?).

Then, as I was walking through a meadow area some ideas literally hit me.  There at my knees was a clump of Sweet Everlasting (Pseudognaphalium obtusifolium) and around the bend was some tall snakeroot (Ageratina altissima).  Both of these plants stood out because of the large clusters of small white flowers.

The woolly hairs on Sweet Everlasting can catch
the light and brighten up the whole plant.
Sweet Everlasting is a native annual that grows well on medium to dry well drained soils.  Like many native annuals they grow well on disturbed sites, especially those will few other plants established.  Those growing in my yard are along the edges of mowed paths and in some of the drier planting beds.  The flowers consist of tightly bunched disk flowers only, no petals (ray flowers).  The narrow leaves are medium to light green on top and white-woolly on the bottom,  The stems are also covered with woolly hairs. As the name implies, the stems and flowers will last for a long time and can be used in dried flower arrangements.  When crushed the stems and leaves have a curry-like fragrance.

Ripe seeds have a fuzzy appendage that will catch the wind, helping with seed dispersal.  I have had some difficulty starting these from seed indoors.  They seem to do much better growing outdoors.  The tiny seeds need light to germinate so they should be sown on the soil surface and pressed in, not buried.

The leaves of Tall Snakeroot are held on long petioles, 1/2  to 2" and are disposed on
opposite sides of the stem.  The length of the petiole and the relatively
broad leaves distinguish it from related bonesets and other snakeroots.

I first noticed Tall Snakeroot (Ageratina altissima, formerly Eupatorium rugosum) growing in a shady area as I was clearing stiltgrass last year.  This year I am seeing it in multiple locations.  I don't know if it is spreading, or I am just getting better at finding it.  Similar to sweet everlasting, these flowers have only disk florets.  The bright white flowers are clustered together in broad heads, making them easy to spot at a distance.  While not a favorite plant for deer, I have noticed some nibbling of the leaves and flowers.

Normally growing 3' tall or more this may be a little tall for the front of a border, but some of mine have flopped over and they look fine at 8-12".  There is a selection named 'Chocolate', identified and developed at the Mt. Cuba Center.  It has burgundy toned foliage.

The 'deer-pruned' turtleheads are bushy and just the right height for the front of a border.
The last non-aster, white flower I came across this past week was White Turtlehead (Chelone glabra).  There grow well in medium to moist soils and part sun.  Under ideal conditions these will grow to about 3' tall.  This is a great plant for use in a rain garden.  It is generally deer resistant, but like with the snakeroot, my deer nibble on them a bit.  This was actually a benefit, after first flush of flowers had been chewed off, the plant came back lower and bushier, with more flowers.