My initial thought was that the third Heronswood Open House for 2011 would be rained out. Saturday (16 July) at the garden began with a persistent, soaking rain. But that gradually tapered off to an intermittent drizzle, and the day finally ended warm and sunny. Some 221 attended the event.

I regularly feel a little overwhelmed by the number of different plants at Heronswood; the number is somewhere in the neighborhood of 5000 discrete entries. I have no horticultural training, and most of these plants are exotic and new to me. I have plenty of knowledge of plants (physiology, anatomy, genetics, biochemistry, taxonomy), and I have spent my working life thinking about plants and working with them in one capacity or another. But I’ve never before studied ornamentally and horticulturally important plants. My point being that every time I visit Heronswood is a learning experience.

I generally become really familiar with two or three new plants during a visit. Often it’s a plant that I’ve never noticed before that’s now in flower. Or sometimes the awareness comes as a result of being asked to identify a plant during the Open House. Such was the case with Tropaeolum speciosum, Scottish flame flower or flame nasturtium. The flower looked familiar, but with the lobed leaves, I could not place it.

Tropaeolum speciosum

Had the leaves been less deeply lobed, I might have recognized it as a “nasturtium” and been spared the embarrassment of being in the position of an expert without an authoritative answer—c’est la vie. “Nasturtium” is misleading, though; Nasturtium (or watercress) is a genus in the mustard family (Brassicaceae), and refers to the edible plants that are cultivated around the world as a leafy vegetable with reputed cancer inhibiting characteristics. Tropaeolum is entirely different, despite the common garden “nasturtium” (Tropaeolum majus). Tropaeolum now the single genus in the family Tropaeolaceae, though that was not always so; there are lots of old, discarded genus names in the family that taxonomist call “illegitimate, superfluous”. There are about 80 species in the family in addition to T. speciosum. These plants are native to Central and South America; Scottish flame flower arose in Chile.

My other find was Alangium platanifolium; this one was by luck. This is a small tree or large shrub native to East Asia, often with multiple trunks. It does well as an understory plant or at margin of a woodland garden, which is where this one is growing. The leaves light green and shaped, roughly, like a sycamore leaf (hence the specific name, platanifolium) or maybe more like a maple. As with a maple, the leaves turn yellow in fall. It will grow to be 10 feet tall and 5 feet wide in 10 years and is hardy to USDA zone 7. Some authorities place the tree in the family Alangiaceae, but USDA Germplasm Resources Information Network assigns it to Cornaceae, the dogwood family.

Alangium platanifolium

Alangium platanifolium

The tree itself is pretty enough, but it is the flowers that attracted me. They are unusual and apparently fragrant. They are cream colored and appear during summer. As seen in the photos, on this tree, they have not yet opened. But what I take to be petals without sepals roll back to reveal multiple stamens ringing a solitary pistil. Flowers later produce a pendulous, oval fruit that becomes light blue as fall color develops. It would make a great addition to any woodland garden.

Alangium platanifolium

Alangium platanifolium

Alangium platanifolium

During the Open House, the garden, despite but probably also because of the rain, was lovely. It will be just as lovely at the last Open House of the year on 10 September. Come see it.

Veronicastrum virginicum

Acer palmatum ‘Shindeshojo’

Lichen on Maple

Acer pseudosieboidianum

Thalictrum delavayi

Geranium himalayense