Meadow sage under the microscope

[Microscopy_is_fun]

The meadow sage (Salvia pratensis) is a pretty common plant in Europe, Asia and northern Africa. It likes sunny, non-fertilized meadows and typically blooms from end of May into June. As can be seen from Fig. 1, the plant can be quite abundant in some places. The picture was taken in the south of Austria where the blue sage grows in happy coexistence with yellow rattle (Rhinantus sp.), yielding a colourful appearance.

The meadow sage smells and tastes very similar to the common sage (Salvia officinalis), yet less intense, making it less popular for being used in infusions and codiments.



Fig. 2 show the habitus of the plant, which is typically between 20 and 60cm tall.


In our garden, several of those plants grow in places where we don't mow, and insects are happy to sip from the nectar which is produced plentifully by the plant. The meadow sage uses a smart trick to spread its pollen, as can be seen from Fig. 3: the nectary (NE) is located deep in the back of the flower, close to the ovary (OV). When an insect wants to reach the nectary, it has to push away the shield (SH) which is connected to the pollen (PO) carrying anthers (AN). In this way the anthers move downwards, releasing pollen onto the back of the insect. When the insect moves to the next flower, the pollen are released to the stigma (ST).

[Microscopy_is_fun]

I used the stem of one plant to watch it under the microscope. For this purpose, I fixed the stem in a mix of ethanol, formalin and acetic acid (AFA). Afer 24hrs, the AFA was replaced by 70% ethanol, followed by embedding in PEG (12hrs in water/20%PEG, 12hrs in water/50% PEG, and finally 12hrs in pure PEG (at 60°C). The embedded samples could then be sliced on a sledge microtome, and the 20µm thick slices where stained in Etzold FCA (fuchsine, chrysoidine, astra blue). The delicate stem with the empty space in the middle survived the procedure quite well, and the various tissues are well differentiated (Fig. 4). The image is a panorama of four individual pictures stitched together in Lightroom. I used a 5x objective for capturing the images.



Fig. 5 gives a detailled view of the same stem, and xylem (XY), phloem (PH), cambium (KA) and collenchyma (KO) can be identified fairly straightforward.

[Alexander]

Nice cuts! Very well done!

[FatBassPlayer]

Spectacular! Thank you for sharing.

[Hobbyst46]

Spectacular! Thank you for sharing.

Likewise !

[LouiseScot]

Very professional, and an awesome location!
Louise

[Microscopy_is_fun]

@Louise, Hobbyst46, FatBassPlayer Alexander: thanks for your encouraging feedback!

The stem actually turned out quite well. I also had a look at the leaves, searching for the glandular hairs and the trichomes. Making thin (<20µm) section sof the leaves turned out to be a difficult task. But finally I was able to mount at least one section, see Fig. 6 (middle rip) taken with a 10x objective and Fig. 7 (detail of the leaf with trichome), taken with 40x objective. I couldn't find the glandular hairs, origin of the sage's essential oils. Maybe it's better to just make a reflected light micrograph of a non-processed leaf, I'll keep trying.