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  7. ›Polemonium
Blue Jacob's Ladder
Plate 1 of 9. (c) Dmitry Ivanov, some rights reserved (CC BY-NC), uploaded by Dmitry Ivanov · via iNaturalist

Blue Jacob's Ladder

Polemonium caeruleum

Polemonium caeruleum, known as Jacob's-ladder or Greek valerian, is a hardy perennial flowering plant. The plant produces cup-shaped, blue or white flowers. It is native to temperate regions of Europe. It is the type species of the phlox family, Polemoniaceae.

Continue reading on Wikipedia

From the article Polemonium caeruleum on Wikipedia (CC BY-SA), quoted section by section

§1

Range & habitat

The plant is native to damp grasslands, woodlands, meadows and rocky areas in temperate areas of Europe and northern Asia.

Wikipedia: “Habitat”

§2

At the table

Polemonium caeruleum was voted the county flower of Derbyshire in 2002 following a poll by the wild plant conservation charity Plantlife.

Wikipedia: “Other uses”

§3

How it is grown

The plant normally prefers soil that is rich in moisture and lime with partial shade. Normally hardy, some cultivars (e.g. 'Blue Pearl') behave as tender biennials, which means they are effectively annuals in cooler climates (below hardiness zone 6). The plant is known to have a few landscape uses as well such as attracting beneficial insects. The plant itself is convenient for container planting due to the shape of its growth. The flower may be presented as a cut flower or foliage and may be added to bouquets for its pleasant smell. It can be grown in a perennial border or rock garden. Cultivars include:

'Album' (white flowered) 'Blue Pearl' 'Brise d'Anjou' 'White Pearl' (white flowered) 'Snow and Sapphires' (variegated foliage) The plant does not have serious insect or disease problems. Leaf spot and powdery mildew can be problems, particularly in humid climates. The foliage may scorch if the plant gets too much sunlight. The leaflet tips will brown if soils are allowed to dry out. The foliage will generally decline and become less attractive as the summer progresses. It is important to keep an eye out for slugs.

Wikipedia: “Cultivation”

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Where it lives

Recorded sightings

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geo-referenced records in GBIF, from museums, herbaria and field observers.

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In the stacks

Searching the stacks…

Every page naming Polemonium caeruleum in the Biodiversity Heritage Library →

This page is assembled live from iNaturalist, GBIF, Wikipedia, the Source Library and the Internet Archive. It is not yet part of the hand-edited codex. iNaturalist taxon 51704.