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North American Delphinium Species 2b

D. nuttallii

A guide to stages in seedling development

Nutall's larkspur is found is found west of the Cascade mountain range and along the Columbia River Gorge region in Oregon and Washington State according to "Flora of the Pacific Northwest" by Hitchcock & Cronquist, 1976.

Seed, collected from the Columbia River Gorge region of the western U.S.A., was sown in multipurpose compost and left exposed to the weather during winter. No germination was noted that year but one plant was seen during the summer after a second winter. The picture shows the pot during January of the third winter, with several delphinium seedlings emerging from the moss. Removing the moss revealed a large number of seedlings with true leaves and roots growing from tubers.

One of the seedlings, presumably that seen during 2000, had a root tuber about 10mm in diameter. The remainder had very small root tubers. These seedlings had probably germinated in the spring of 2000 but had not been noticed, perhaps because they did not develop any true leaves before becoming dormant.

Seedlings were carefully extracted and re-potted in fresh compost. All seedlings grew quickly and, by late March, the largest was developing a flower stem. Plants were re-potted into 1litre pots for flowering.

Leaves on the stem became larger and more serrated as the stem developed and thickened. The plant from the largest tuber had a stem approximately 8mm in diameter. Plants from tiny tubers had slender (2-3mm), stiff stems.

Flower spikes developed in May/June with small florets (33mm across) held on long pedicels giving a broad-based tapering bloom. Plants that grew from tiny tubers were flowering for the first time with about 20 florets in the bloom.The largest plant, probably in its second flowering season, had 41 florets in the bloom with pedicels 230 mm long at the base of the spike and was 1.35 m tall. Ten secondary flower stems developed from leaf axils below the bloom. This doubling of the number of florets in the bloom of older plants is also seen in D. trollifolium.

Flower colour varied from purple to deep violet with some plants having flowers of a brilliant gentian blue. A notable feature of the flowers is that the lower pair of petals (honey leaves) completely obscure the anthers. These also have beards of whitish hairs.

The flowers were very attractive to bees and a large amount of seed was obtained. The plants became dormant after setting seed.

Species identity There are some inconsistencies between the features of D. nuttallii described in the Flora cited above and the plants grown. In particular, the Flora indicates that the raceme is compact with pedicels often < sepals, which was certainly not the case. It seems unlikely that this was a consequence of the cultivation method because blooms of D. burkei grown under identical conditions were compact with florets on very short pedicels.
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