Plant or Alga?

[linuxusr]

I was surprised to find a helix, not the usual microscopial observation:

https://imgur.com/a/hNd34fu

I infuse timothy hay and alfalfa, so this could be a plant part. I think I’ll take some samples from each plant, separate the parts in different petri dishes, and take a look under my stereomicroscope.

It’d be nice to have a baseline to know whether I’m looking at a plant part or a micro specimen generated from the infusion, ambient air, etc.

I see no chloroplasts here, so I’m thinking this must be a plant part. What do you think?

[perrywespa]

You didn't mention magnification and I'm no expert, but I think it's plant fiber. This is based on seeing similar images in the past. I'm sure someone will correct or confirm my suspicion.

[mrsonchus]

You didn't mention magnification and I'm no expert, but I think it's plant fiber. This is based on seeing similar images in the past. I'm sure someone will correct or confirm my suspicion.

Yes, it's a section of a Xylem vessel-element's lignified secondary-wall by the looks of it - primary Xylem I think.

Found an image from an Aloe dissection I made a few years back,

websize_vessels_in_aloe_leaf.JPG (110.85 KiB) Viewed 2112 times

Certainly looks like a candidate.

[linuxusr]

You didn't mention magnification and I'm no expert, but I think it's plant fiber. This is based on seeing similar images in the past. I'm sure someone will correct or confirm my suspicion.

Yes, it's a section of a Xylem vessel-element's lignified secondary-wall by the looks of it - primary Xylem I think.

Found an image from an Aloe dissection I made a few years back,
websize_vessels_in_aloe_leaf.JPG

Certainly looks like a candidate.

This is the ticket mrsonchus. Thank you so much. Do you think that the helical form confers a structural benefit? What does it mean that the secondary wall is lignified? You mentioned primary xylem. Is there also secondary xylem?

[mrsonchus]

Aha! Form & Function!
Yes, lignin - a hard substance found acting as reinforcement for parts of a plant that need it, especially in the cell-walls of the conducting 'tubes' of water (and other things), known as Xylem.
The thickening rings, spirals. helices etc give the support needed to keep these vessels open, a little like the cartilage in our own windpipes, which I think are actually rings rather than spiral?

Primary thickening occurs whilst a (part of a) plant is still growing, expanding and certainly lengthening in the case of stems. The lignification is need 'from the off' as it were, but must when added at this primary stage, be capable of expanding along with the vessels' cell walls - hence primary lignification tends to be either discrete rings, spirals or helices, which will be able to move along with a lengthening cell-wall, similar to the spirals in those stretchy tubes a vacuum cleaner may have for it's flexible and stretchable tool-extensions. Maybe a case of similar form/functionality....

Secondary reinforcement, again with lignin, is added after a cell has attained it's full size/length etc, and so doesn't need to be of a form that allows stretching - the upshot of which 'secondary' thickening takes a more solid form, in fact there's a progression of the form-function example observable in a section through the right orientation of a stem's vascular bundle - LS shows this better than TS usually. Ultimately the lignification may well be almost a complete 'skin' around a vessel - very strong, unable to stretch without ruin, and definitely able to hold-open the vessel 'tube'... In fact helices can be found at the crossover of primary and secondary growth - so could be either, but I think more likely primary - contradicting my earlier response....

'Primary' and 'Secondary' growth is NOT the same meaning as 'Primary' and 'Secondary' cell-walls - both of which are very important to understand if the inner workings of plants are to be uncovered!


Here's a half-decent image of a longitudinal section through such a vascular bundle - the progression (L-->R) from discrete ring to the more solid lignification is in part visible, but not up to the almost solid lignification I mentioned above - the orientation of the section was not optimal, but some nice stretching may be seen of the primary cell-walls with rings keeping the vessel functional as the cells stretch... This slide image does however show all stages (wall-types) except the last one labelled 'E' in the B&W snipped image. The stage 'E' is almost solid (not as in filling the interior of the vessel, but as being like a continuous sheet of lignified cell-wall around the actual interior 'tube').- certainly not able to stretch longitudinally!



Here's a great example from a search response for jstor - a document archive I regularly read as many of the papers are free....

Capture.JPG (97.85 KiB) Viewed 2069 times

See how the lignification becomes progressively stronger but less able to stretch as the lignin is laid down when the cells are finished elongation - as opposed to the earlier rings etc formed whilst elongation was actually occuring. I could go on for days, apologies for the rather long-winded response....

[linuxusr]

The latter from jstor is a very clear graphic. (Thank you for the jstor source). You can clearly see that from the second part of the proto-xylem through the secondary wall thickening that each stage becomes more structurally sound but maintaining the property of being able to bend. Is that tensile strength? The specimen I showed you seems to match letter D in the diagram.

Are you saying that lignin is the primary substance that makes up these structures? And could you say that these structures are lignifying with respect to maintaining the structure of the xylem?

When I make my infusions I want to distinguish the plant parts from specimens that are "generated" from the infusion. To sort this I separated the parts of the timothy hay I use and put them in a petri dish. I will examine them 40x TM and 100x TM and see what I see. The xylem is a little thick to put under a coverslip, Every I look at this stuff dry, I might wet it and create a wet mount and try to tease apart the xylem with dissecting needs and see if I can't get a look inside. I'll let you know.

Thank you for this most interesting presentation!