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North American Delphinium Species

D. leucophaeum

A guide to stages in seedling development

D. leucophaeum is listed in the Flora of North America as a sub-species, 'ochroleucum', of D. nuttallii that it closely resembles except in the colour of the flower, which is pure white apart from blue tips of the upper petals. This delphinium is found locally on rocky outcrops and rocky meadows in northern Oregon close to the Willamette and Columbia rivers.

Seeds were sown in mid-January 2004 on the surface of peat-based multi-purpose compost and lightly covered with compost and a thin layer of grit. The pot was left outdoors exposed to the weather, which included periods of rain and some overnight frost. A few seeds germinated by the end of May but there was no significant germination until after a second winter, when many seedlings appeared in May 2005. These did not appear to develop further before disappearing and remained in the pot until spring 2006, when the first true leaves began to emerge through the moss covering the surface in late March. It seemed desirable to 'rescue' the delphiniums before root entanglement resulted in too much damage. This was very difficult and it was necessary to wash out all the compost. The delphinium seedlings were found to have tiny round tubers about 2mm in diameter with little root. Their chances of survival seemed small, so groups of ten or more seedlings were replanted together in large pots of compost.

To our surprise, these seedlings recovered well and grew steadily larger. Flower stems began developing in early June, as seen in the picture below.

Rapid growth continued during the extremely hot weather in June with many stems having flowers opening at the start of July, as seen in the picture below. The flowers set seed but the plants were growing close to plants of D. nuttallii with open flowers so it will be interesting to determine if the seeds from D. leucophaeum yield plants with blue flowers as a result of hybridisation.

For several years, Shirley has grown D. leucophaeum successfully under glass. The picture of a single flower above was taken by pushing the flower stem through a slot cut in a sheet of blue paper, placing this 'flower-page' on a document scanner and then scanning the image into the computer.

The most fascinating feature of this species is the presence of blue petals in the eye of a white flower. This does not normally occur in garden hybrid delphiniums with white flowers, even if these have blue-flowered cultivars in their parentage. We are uncertain if there are other species in which this 'inversion' of the sepal and eye colour occurs but the description of D.albiflorum, a species from northern Greece and Bulgaria, suggests that it is possibly another example.

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