This X-ray CT scanned Freesia is from the species Freesia alba which is native to the cape of South Africa. Freesias are known for their funnel shaped flowers and are part of the Iris family.
The ‘hidden half’ of Freesias are particularly interesting as the flower develops from an underground corm. The corm is an organ that looks similar to a bulb but develops from different tissues in the plant. Corms develop from the stem and contains solid tissue whilst a bulb is made up from modified leaves and consists of layers of scales.
Corms and bulbs are food storage organs that allow the plants to survive in a dormant state through winter.
In this image you can see the root system is developing from the both the root and the corm, which is part of the stem. It is surprisingly common that roots form from the stem in plants.
3D Root Architecture
This video of the freesia shows the root architecture that has developed over 21 days of growth and as you can see the plant is fairly pot bound. There are three distinct root structures within this plant, the roots emanating from the main corm (shown in blue), the roots emanating from the stem (shown in orange) and roots emanating from the developing new corm (shown in green).
The cross sections were taken through a freesia primary root (upper panel) and higher order root (lower panel) imaged using a confocal microscope.
Both root sections reveals central zones called the stele. The small red dots in the stele are xylem which transport water and nutrients. The bright green/cyan dots are phloem which transport nutrients.
Emerging from the primary root stele is a new lateral root that passes through overlying endodermal, cortical and epidermal cells.
Both root sections contain a multi-layered tissue termed the cortex positioned between the stele and outer epidermal layer (red). The primary root appears to contain a fluorescent sub-epidermal layer termed an exodermis (cyan)