Helianthus petiolaris [Prairie Sunflower]

[Andrea B.]

Blum, A.G. (2021) Helianthus petiolaris Nutt. (Asteraceae) Prairie Sunflower. Flowers photographed in ultraviolet and visible light. https://www.ultravio...irie-sunflower/

 

Synonyms:

• Helianthus couplandii B.Boivin
  
• Helianthus integrifolius Nutt.
  
• Helianthus patens Lehm.
  
• Helianthus canescens (A.Gray) S.Watson, syn of var. canescens
  
• Helianthus canus (Britton) Wooton & Standl., syn of var. canescens
  

Other Common Names:

• Plains Sunflower
  

Comment:

While not at all fragile, Prairie Sunflower has an airier, less robust appearance than its cousin, the big-leaved, sturdy, larger Common Sunflower (H. annuus).

 

To secure an identification, look for a cluster of the white-hairy tips of the disk chaff in the center of an H. petiolaris disk. Also, note that the H. petiolaris phyllaries are narrow and lanceolate with non-ciliate margins unlike the ciliate, ovate phyllaries of H. annuus. The disk flowers of H. petiolaris may be either dark red or dark purple.

 

H. petiolaris is widely spread across the US. I have seen it on the dunes of Sandy Hook in New Jersey as well as along the roadsides around Santa Fe, New Mexico.

 

Sunflowers like H. petiolaris are a favorite of UV photographers because they have a UV-dark central bulls-eye which serves as a known test pattern for confirmation of the UV-worthiness of UV-pass filters or UV-capable lenses.

 

References:

1. Allred, Kelly W., Jercinovic, Eugene M., Ivey, Robert DeWitt (2021) Flora Neomexicana III: An Illustrated Identification Manual, Second Edition, Part 2, Helianthus Key, page nnn. Print on demand at lulu.com.

2. Weber, William A. (1976) Rocky Mountain Flora, 5th Ed. Helianthus Key, page 154. University Press of Colorado, Niwot, Colorado.

3. SEINet Arizona-New Mexico Chapter (acc 08 Aug 2021) Helianthus petiolaris.

This is a southwestern biodiversity organization making use of the Symbiota portal software.

 

 

SET 1

Eldorado at Santa Fe, Santa Fe, New Mexico, USA

Near the intersection of Avenida Eldorado & Aster Way.

07 Aug 2021

Wildflower

 

Equipment [Nikon D610-broadband + Nikon 105mm f/4.5 UV-Nikkor]

 

Visible Light [f/11 for 1/13" @ ISO-100 under Ambient Skylight with Baader UVIR-Block Filter]

 

 

Ultraviolet Light [f/11 for 1/30" @ ISO-200 with SB-140 UV-Flash and BaaderU UV-Pass Filter]

 

 

Ultraviolet Light [f/11 for 1/30" @ ISO-200 with SB-140 UV-Flash and AndreaU-MkII UV-Pass Filter]

 

 

Ultraviolet Light [f/11 for 1/30" @ ISO-200 with SB-140 UV-Flash and U-340 x 4.00 mm UV-Pass Filter]

This filter was not IR-blocked. At 4.0 mm thickness it passes mostly UV, but you can see that the central bulls-eye is slightly less dark than in the other two UV photos.

 

 

Infrared Light [f/11 for 1/40" @ ISO-400 under Ambient Skylight with B+W 092 IR-Pass Filter]

 

 

UV+Blue+Green [f/11 for 1/13" @ ISO-400 under Ambient Skylight with UG5(1.5 mm) + S8612(1.75 mm)]

 

Leaves

These are small leaves from new growth. Their lanceolate shape is like that of older, larger leaves.

 

 

Helianthus annuus Reference Photo: Involucre

The phyllaries are wide with long points.

The margins are ciliate (fringed).

 

 

H. petiolaris Abaxial View

Note the narrow phyllaries as compared to those of H. annuus in the preceding reference photo.

Also the phyllary margins lack a distinct ciliate fringe.

 

Visible Light [f/11 for 1/6" @ ISO-200 under Ambient Skylight with Baader UVIR-Block Filter]

 

 

Ultraviolet Light [f/11 for 1/30" @ ISO-200 with SB-140 UV-Flash and BaaderU UV-Pass Filter]

 

 

Infrared Light [f/16 for 1/15" @ ISO-200 under Ambient Skylight with B+W 092 IR-Pass Filter]

[GaryR]

I enjoyed seeing the crispness of the BadderU, compared AndreaU and U340. Also noticed the petals seem to be a brighter yellow with the Baader. Is that post processing or the Baader?

[colinbm]

Another lovely set Andrea good to see them all.

[Andrea B.]

Gary, you ask an interesting question! I think the yellow difference between the BaaderU and the AndreaU-MkII is probably just a minor editing difference. But that said, I should note that we have not really made any attempts here on UVP to deal with false-color saturation.

 

To do that we would need to know (amongst other factors) the transmission peaks of both filters and the trans amount at the peak as well as the bandwidth of the two filters. Then we would need to try to make photos from the two different filters which compensated for those two factors in a fair way that would produce "equivalently saturated" raw files. I'm not even sure how to do this or if it can be done.

 

An additional complication would be that we should know the bandwidth of UV reflectivity of the flower and how that relates to the two filter peaks. Maybe one filter could give us more false-yellow than another because that filter's peak lies in the central area of the UV reflectivity which produces false yellow?

 

I'm just throwing out a few ideas which occurred off the top o' me head, so I could be missing some salient factors....or I maybe have this all wrong. But it does seem like quite a can of worms to deal with.

*****

 

I am not sure about the sharpness between all the filters. It looks like the focus point may be slightly different between the two filters. I've always found the newest AU-MkII to produce the same level of detail as the BU. I haven't really looked at differences in acutance.

*****

 

Well, forgive me for rambling on here....but our UVP members always challenge me to think more and I truly value that. I hope others are learning as much as I have from our forum.

[GaryR]

Thanks for your reply Andrea. The color transmission isn't a big issue for me, but the BU does seem to have a slight contrast edge over the AndreaU. I'm always intrigued by blackness and contrast of the BU. Still on my future purchase list, but I worry about how delicate these filters are.

[Andrea B.]

Gary, I've found the BaaderUs to be tough enough as long as you don't step on them. (Yes, I did that once. That's a crunch you don't ever want to hear under your foot.)

 

BaaderUs can get scratched a bit. But I use BaaderUs out "in the field", as they say. So I've accidently dropped them on dirt or gravel, had bees bash into them, had the wind blow over a tripod with BU on the lens, gotten them sticky with pollen and dust and so forth. Their few little scratches have no effect on any photos that I could ever detect. The current set I'm using I have had for about 10 years now (I think) with no plans to replace them even though they have accumulated those little scratches.

 

Of course a really deep scratch in the dichroic coating could affect a photo outcome. Thankfully I haven't done that.

 

I will note that the 48 mm ring mount (not the threaded side) is somewhat thinner than I would like. If the lens falls onto the ground with the BaaderU mounted, then it is possible to dent that ring. (Yes, I did that once. Thread side ok though.)

Currently my BU and the Baader UV/IR-Cut are mounted in one of these Baader filter holders with a Hyperion step-ring. While those might offer a bit of protection, I think they are somewhat expensive. The Hyperion stuff does make handling and mounting the BU easier for me. YMMV.

[Andy Perrin]

Andrea, does an ordinary 52-48mm step down ring work for Baader 2"?

[Andrea B.]

Yes it does. I also use that.

[GaryR]

Andrea, Yes, I did see your shattered BU post.

Glad to hear that the BaaderU is reasonably resilient.

Thanks for the filter holder info.

[Cadmium]

Don't forget about the slug!

Very nice photos. I also like the IR.

[Andrea B.]

I did forget until you mentioned it.

That was totally yukky!