Herbertia lahue

A gorgeous little summer flowering Iris relative producing attractively marked violet flowers on short stems just above the ground. Although this is widely distributed in the USA it’s of doubtful hardiness and may need protection, but I recommend trying it in short turf – a technique that works remarkably well with many ‘tender’ bulbs

£6

Dichroa febrifuga

An attractive but tender evergreen woodland shrub with conspicuous heads of pink (or on lime-free soils, blue) star-shaped flowers followed by metallic vivid blue berries - overall very like Hydrangea macrophylla but without the sterile florets.

Apparently most of the plants in cultivation are hybrids between the true Dichroa and Hydrangea macrophylla, but none of the Hydrangea's cold tolerance seems to have found its way into the progeny. Strictly speaking should probably be classified in Hydrangea

Sadly not hardy enough for most UK gardens but worth a try in very mild sheltered sites and will regenerate from the base if cut down by frost - probably not soon enough to flower though. Otherwise a splendid plant for a cool greenhouse
£16

Silphium

A great genus close to the sunflowers that, although often very tall, produce a very compact rootstock and are best displayed among low-growing plants.

Silphium terebinthinaceum

This and S.laciniatum produce among the biggest, most luxuriant leaves of any hardy border perennial.

In this case they are huge and heart-shaped (like a Colocasia or Anthurium?) to 12ins across.

The flower stem is more slender and smooth than laciniatum.
£9

Silphium simpsonii

A smaller species with simple green leaves and golden flowers
£8

Silphium laciniatum

Leaves to 2ft long and impressively lobed, like some huge tropical fern. The stiff bristly upright flower stem is a bonus.

Easy in any fertile, retentive soil, and best at the front of the border where its stature can be appreciated. Perfect for prairie-style plantings.
£9

More Euonymus

Euonymus occidentalis

A modestly sized species with rich red/maroon flowers and good quality deciduous foliage. The fruits are pink capsules with orange seeds.

I've been very impressed with the quality of this American species - perfect for mixed woodland plantings.
£16

Euonymus obovatus

Another North American species - this time a low and creeping, with pale greenish pink flowers followed by pink warty capsules opening to reveal orange seeds
£10

Lindelofia anchusoides

Or L.longiflora - the naming of this plant seems very confused. Anyway, an unaccountably little grown Cynoglossum-like plant with intense azure flowers over dense clumps of leaves. Not at all coarse

Hardy and easy in a sunny well-drained place

£8

Spiraea hayatana

A pleasing medium-sized species with strongly red tinged new growth and heads of white flowers tinged pink at the centre in June.

Like most Spiraea it is easy and hardy.
£12

Ercilla volubilis

An unusual Chilean climber related to Phytolacca with small wavy matt evergreen leaves, and clusters of pink scented fluffy inflorescences in spring. Can be trained on a sunny wall or growing through a large shrub or as ground cover.

Hardy and adaptable with a bit of shelter
£16

Codonopsis

Rather like a climbing Fritillaria is how I'd describe these unusual herbaceous vines. The flowers have the same bell-shape and a similar green and maroon colour scheme, though without the chequering. The markings are just as interesting however.
Often recommended for woodland conditions but adaptable to a variety of rich and not too dry soils where the vine can grow up through shrubs into the light. Watch out for molluscs early on. To 6ft tall. Flowering late summer/autumn.

Codonopsis viridis ex CC 7454

An exquisitely marked species - highly desirable
£8

Codonopsis lanceolata

A particularly tough easy species with substantial jade and maroon bells

£8

Codonopsis cardiophylla

Substantial waxy bells of very pale purple with a rich purple centre. 

Relatively short upright growth and glaucous rounded leaves.

£8

Codonopsis ovata

Elegant nodding pale bells on upright stems over a relatively low-growing plant

£8

Codonopsis pilosula Tangshen

A vigorous climber with pale bells, delicately marked with purple inside

£8

Aconitum lycoctonum moldavicum

This is one of those species where the flowers have a tall narrow hood. The best-known forms have yellowish or off-white flowers but this is a very nice dusky purple form, to about 3ft tall and flowering in late summer. Easy and hardy

£8

Chasmanthe aethiopica

A tender winter flowering bulb similar to Crocosmia. The plumes of scarlet flowers make it a striking greenhouse plant, perhaps for a large pot with plenty of moisture during the growing season. Not invasive.
Not a brilliant photo because they're too tall for the greenhouse staging. I'll keep them on a lower bench next year
£8

Weigela sp. TCM 12-852

An unknown species  from Tom Mitchell. Early flowering with unusually broad fresh green leaves and soft rosy flowers. Rather choice. I like it a lot

£16