Rock Isotome
(Isotoma axillaris)
Rock Isotome (Isotoma axillaris)
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Krzysztof Ziarnek, Kenraiz
CC BY-SA 4.0
Image By:
Krzysztof Ziarnek, Kenraiz
Recorded By:
Copyright:
CC BY-SA 4.0
Copyright Notice:
Photo by: Krzysztof Ziarnek, Kenraiz | License Type: CC BY-SA 4.0 | License URL: https://creativecommons.org/licenses/by/2.0 | Uploader: Kenraiz | Publisher: Wikimedia Commons |



















Estimated Native Range
Summary
Isotoma axillaris, commonly known as Rock Isotome or Showy Isotome, is a small herbaceous perennial native to Australia, particularly found in open woodlands and grasslands. It is also referred to as Blue Star, Star Flower, or Laurentia. This plant typically grows to a height of 50 cm with ascending stems that are often a purplish color and covered with short, soft hairs that become smooth over time. The star-shaped flowers, which are usually blue or mauve, bloom prolifically from September to May, creating a showy display that is particularly attractive to gardeners.
Rock Isotome is valued for its long flowering season and vibrant star-shaped flowers, which can add a splash of color to rockeries, borders, and container plantings. It is winter hardy to about −1 °C (30 °F) and is best suited to USDA Zone 10. In regions with colder winters, it is often grown as an annual or overwintered indoors. For optimal growth, Rock Isotome requires full sun exposure, medium amounts of water, and well-drained soil. While it is generally easy to maintain, it can be susceptible to root rot if overwatered or planted in poorly drained soils.CC BY-SA 4.0
Rock Isotome is valued for its long flowering season and vibrant star-shaped flowers, which can add a splash of color to rockeries, borders, and container plantings. It is winter hardy to about −1 °C (30 °F) and is best suited to USDA Zone 10. In regions with colder winters, it is often grown as an annual or overwintered indoors. For optimal growth, Rock Isotome requires full sun exposure, medium amounts of water, and well-drained soil. While it is generally easy to maintain, it can be susceptible to root rot if overwatered or planted in poorly drained soils.CC BY-SA 4.0
Plant Description
- Plant Type: Herb
- Height: 0.5-1 feet
- Width: 0.8-1 feet
- Growth Rate: Moderate
- Flower Color: Blue, Purple, White
- Flowering Season: Summer, Fall
- Leaf Retention: Evergreen
Growth Requirements
- Sun: Full Sun
- Water: Medium
- Drainage: Medium, Fast
Common Uses
Border Plant, Groundcover, Showy Flowers
Natural Habitat
Open woodlands and grasslands in Australia
Other Names
Common Names: Showy Isotome, Laurentia
Scientific Names: , Isotoma axillaris, Laurentia axillaris, Lithotoma axillaris, Isotoma senecioides, Isotoma senecioides var. subpinnatifida, Lobelia fleuryana, Lobelia senecioides, Lobelia senecionis,
GBIF Accepted Name: Lithotoma axillaris (Lindl.) E.B.Knox