Flowers in Ultraviolet
Arranged by Plant Family

Photography by Bjørn Rørslett/NN

The compilation of species will continue to be updated at irregular intervals. All species listed here have been documented, and links are added whenever I can find spare time for updating. These images are made for illustrative purposes, not as artistic statements per se. However, there are lots of food for thought in the convoluted ways Nature expresses itself, so for once the artist can step backand let the subjects speak for themselves. "Das Ding an Sich" to paraphrase Kant, or Eigenvalue of Nature.

If you are unfamiliar with the botany, just select any species indicated as having a "strong" response to learn how this looks. Potentilla anserina may constitute an introductory example. In case you wonder about the family and species selection, these are plants readily available to me.

However, not all species have the typical bull's-eye UV pattern, which may be confined to symmetrical flowers. Nevertheless flowers may exhibit a virtually endless variety of spectral signatures. Just take a look at this modest plant, Glechoma hederacea, to get an impression of the near bewildering spectral diversity that exists.

The UV range of the spectrum has no predefined colours, so we are free to assign any colour we like. There are no rules set in stone for this at all. I set out my UV work using film, so in principle would like the "film UV colours" (blue with UV absorbance often shown in reddish hues) to prevail. Different spectral response of the UV bandpass filters applied in these years, in conjunction with changing behaviour of the digital cameras and their RAW-file converters, have made this aim impossible to uphold. Thus, don't compare colours, compare patterns. I'm currently writing a tutorial on how the UV "colours" are created and how they should be interpreted, but for the time being, just enjoy the images like the pollinators enjoy their targeted flowers.

UV fluorescence may be a common trait to most flowers, but might be of temporary occurrence for parts of the flower. Anthers, style, and pollen grains occasionally are seen to fluoresce. Strong fluorescence has been noted from nectar glands (Angelica sylvestris) and several other species. Some species show fluorescence of the non-fertilised stigmas, but this trait is difficult to document with my normal technical approach. Fluorescence from outside of the bracts is exhibited by some species. As far as the photography is concerned, the main issue with flower fluorescence is its transient behaviour. It may be present, but the flowers collected for photography don't appear to fluoresce simply because the floral development is in the "wrong" stage. With fluorescent pollen grains, their size often are at or below the detection limit unless quite high magnification is employed, thus calling for a true photomacropgraphic approach. The fluorescing pollen of Mirabilis jalapa (Four o'Clock) has been documented using this method.

In case you are curious as to why the species might have these patterns, read this to learn more. UV-absorbing substances (flavonyl glucosides) are instrumental in bringing about the fascinating pollinating guide patterns. UV marks on flowers are but a logical extension of the visual pollinating clues provided by evolution in Nature. When a flower is stated to lack UV marks, it simply means the signals emitted are directed towards pollinators which can "see" in alternate spectral bands, outside the UV range. If the flower absorbs UV all over the floral parts, it may appear visually in a "UV-complementary" colour even to pollinators capable of seeing in UV. We can only speculate as to the rendition of that complementary colour, but if say the insect is modelled as seeing UV as "blue", blue as "green", and green as "red", then the UV complementary would be yellow. Thus, a UV-absorbing yellow flower still would come across as "yellow" even for an insect (or so it might seem, but who are we to know such things anyway).

A final word of warning is that UV photography as such has lots of technical pitfalls and issues. You have to make absolutely sure your camera really records UV patterns, and in order to ensure this, careful testing of your setup is necessary. This has become even more important in the digital era, as outlined elsewhere in my UV/IR tutorial. Read in particular about the issues with IR contamination described there.

Flower Colour Ultraviolet Features

(Strong, intermediate etc. refer to a UV-visible bull's-eye pattern of the flower. Other patterns may appear as duly noted)

Narcissus pseudonarcissus L. Bright-deep yellow Not a bull's eye pattern, but the flower appears flamed in UV light with alternating high- and low-UV reflecting stripes
Angelica sylvestris L. White Low UV reflectance of entire flower, but very strong UV fluorescence of the nectar glands
Carum carvi L. Dullish white or reddish  
Vinca minor L. Light violet Strong UV reflectance, but a bull's eye pattern is not very prominently developed. High reflectance in near IR, though


Achillea millefolium L. Dullish white Very weak
Anthemis tinctoria L. Dark yellow Intermediate - strong, some UV fluorescence
Arnica angustfifolia Vahl Dark yellow Very strong bull's eye pattern
Aster tripolium L. Light violet Intermediate, coincides with visual pattern
Bidens sp. Deep yellow Big, very prominent UV marks
Calendula officinalis L. Orange Strong bull's eye
Centaurea jacea L. Purple Intermediate - strong
Chrysanthemum segetum L. Bright yellow None (all the flower head absorbs UV)
Cicerbita alpina (L.)Wallr. Light violet Intermediate
Cichorium intybus L. Light blue Intermediate - strong UV marking
Crepis biennis L. Bright yellow Strong, but not well delineated
Doronicum orientale Hoffm. Deep yellow Very strong bull's eye pattern. UV fluorescence.
Hieracium aurantiacum L. Reddish Unusual, chequered pattern
Hieracium subg. Pilosella Yellow Variegated UV pattern
Hieracium sect. Prenathaea Yellow Strong
Hieracium sect. Sylvatica Yellow Strong
Lapsana communis L. Yellow Strong
Leucanthemum vulgare Lam. White petals, yellow centre disc Weak, some zonation across central floral disc, low UV reflectance of outer flower areas
Leontodon autumnale L. Yellow Strong
Mycelia muralis (L.)Dum. Light yellow Intermediate - strong
Petasites hybridus (L.)Gaertner, Meyer & Scherb. Very light pink, rarely light yellow Strong UV fluorescence
Rudbeckia hirta L. Bright yellow Strong. Very large and prominent UV marks
Senecio aquaticus Hill. Bright yellow Very strong, entire centre absorbs UV
Senecio jacobea L. Deep yellow Very strong
Senecio viscosus L. Light yellow Ray flowers strongly reflect UV
Sonchus arvensis L. Deep yellow Strong bull's eye pattern, but UV delineation against the flower periphery is blurred (a common trait to UV marks of many composite flowers, by the way)
Sonchus oleraceus L. Light yellow Strong
Tanacetum vulgare L. Deep yellow Negligible. Some zonation across the floral discs on the onset of flowering
Taraxum vulgare Web. Yellow Usually extremely pronounced, but quite variable extent of bull's-eye pattern. Dandelions are really a cluster of related, apomictic microspecies. This helps explain why the UV markings may vary so much
Tragopogon pratensis L. ssp. minor (Mill.)Hartm. Deep yellow No typical bull's eye pattern, but strongly UV-reflective bracts contribute to form a two-zoned flower head
Tripleurospermum maritium (L.)W.D.J. Koch White Strong bull's eye
Tussilago farfara L. Yellow Strong bull's-eye pattern, but variable UV reflectance of outer petals


Alliaria petiolata (Bib.)Cavara & Grande White Intermediate. Anthers and pollen absorb strongly in UV
Barbarea vulgaris (L.)R.Br. Yellow Strong
Berteroa incana (L.)DC. White Not a typical bull's eye pattern in its small flowers. However, there are floral buds and stigma with a prominent UV fluorescence
Brassica nigra (L.) Koch Yellow Strong bull's eye pattern
Bunias orientalis L. Light yellow No bull's eye pattern, but quite high UV reflectance of petals
Erysimum hieracifolium L. Yellow Petals darkish under UV light, buds and non-fertilised flowers show strong UV fluorescence
Hesperis matronalis L. Pink, mauve or purple Intermediate, UV fluorescence
Rorippa sylvestris (L.)Bess. Yellow Intermediate - strong
Sinapis arvensis L. Yellow Very strong bull's-eye pattern, young buds absorb UV, too


Campanula glomerata L. Dark purple Intermediate to strong two-zoned pattern, very high UV reflectance of outer floral parts
Campanula latifolia L. White or blue  
Campanula rapunculoides L. Light violet Intermediate to strong UV marking
Campanula persicifolia L. Deep or sky blue Very high UV reflectance of corolla, high UV absorption from stigma and anthers
Campanula rotundifolia L. Light to sky blue Intermediate, UV marks mainly on pistils and stigma
Campanula trachelium L. Bright-dullish blue, with greyish tint Very high UV reflectance of corolla and buds, stigma absorbs UV, nectaria fluoresce in UV
Jasione montana L. Bright blue Flower heads with a mosaic of UV-absorbing or reflecting areas
Lobelia dortmanna L. White or pinkish purple  


Lonicera perclymemum L. Creamy white Weak
Cerastium arvense L. White Strong
Dianthus deltoides L. Pinkish or light purple Strong, high IR reflectance, UV fluorescence
Lychnis viscaria L. Bright purple Strong, high IR reflectance
Saponaria officinalis L. Light pink Petals and anthers absorb UV, the border of petals do reflect UV
Silene armeria L. Bright purple Intermediate - high UV reflectance, depending on floral stage
Silene dioica (L.)Clairv. Bright purple or red Strong UV pattern, high IR reflectance
Silene uniflora Roth White Intermediate


Calystegia sepium (L.)R.Br. Pinkish or white Intermediate - strong UV pattern
Convolvulus arvensis L. White and pink Intermediate, reflects also strongly in IR
Cuscuta europaea L. ssp. halophyta (Fr.)Hartm. Pinkish white Whole corolla absorbs UV strongly, some UV fluorescence from young flowers


Sedum acre L. Yellow Intermediate - strong
Sedum reflexum    
Sedum telephium L. Light yellowish None
Knautia arvensis (L.)Coult. Purplish-violet Intermediate - strong, unusual chequered UV pattern
Drosera longifolia L. (flowers) White Petals, anthers, and stigmas absorb UV, nectaria have strong UV fluorescence
Drosera longifolia L. (leaves)

(yellowish green, red tentacles)

Leaf blade absorbs UV, viscous fluid drops on insect-catching tentacles have strong UV fluorescence


Andromeda polifolia L. Pink red  
Calluna vulgaris L. Greyish purple  
Erica tetralix L. Pinkish red  
Loiseleuria procumbens (L.)Dum Pinkish white Intermediate - strong


Lathyrus linifolius (Reichard)Bässler Variegated purple - greyish violet No bull's eye pattern, but high UV reflectance of corolla
Lathyrus odoratus L. Pink No bull's eye pattern, but significant UV reflectance of corolla
Lathyrus pratensis L Yellow No bull's eye pattern, but high UV reflectance of corolla
Lotus corniculatus L. Yellow or Reddish tinged Indistinct, variegated stripes on corolla
Vicia sepium L. Mauve or light pink Very weak UV signs, but the corolla does reflect UV and additonally shows fluorescence
Centaurium littorale (Turner) Gilmour Pink or light purple Anthers and stigma strongly absorb UV


Geranium pratense L. Bluish or purple, often with a greyish tinge Variable-sized central UV absorbing spot, combined with UV-absorbing rays radiating outwards. IR reflectance is quite high, too
Geranium sanguineum L. Scarlet or deep purplish red Strong, in combination with a radiating pattern on the petals. Strong IR reflectance
Geranium robertianum L. Light purple Strong bull's-eye marking
Geranium sylvaticum L. Purplish red Very strong bull's-eye pattern. Strong reflectance in near-IR
Hypericum maculatum Cr. Deep yellow Intermediate - strong
Hypericum perforatum L. Deep yellow Intermediate - strong


Glechoma hederacea L. Bluish violet or purple No typical bull's eye pattern, but variegated stripes on petals from UV reflectance. Also distinguished by anthers which both reflect UV and show strong fluorescence under UV light. In addition, whole flower reflects strongly in the near-IR band.
Stachys officinalis (L.)Trev. Purple Large areas of the corolla reflect UV strongly
Gagea lutea (L.)Ker-Gawler Yellow Strong
Gagea minima (L.)Ker-Gawler Yellow Strong
Lilium bulbiferum L. Red Intermediate, some UV fluorescence
Lythrum salicaria L. Purple Intermediate
Mirabilis jalapa L. Yellow Moderate UV reflectance of perianth, but significant UV fluorescence of corolla and pollen


Nuphar lutea (L.)Sibth. & Sm. Yellow  
Nuphar lutea x pumila
(N. spenneriana)
Yellow Strong, unusual circular pattern
Nuphar pumila (Timm)DC. Yellow  
Nymphaea alba L. White Intermediate
Epilobium angustifolium L. Purplish red Weak
Epilobium montanum L. Light red None
Epilobium watsonii Light red  
Oenothera biennis L. Light yellow Prominent and stunningly beautiful UV markings
Oxalis fontana Bunge Light yellow Strong
Eschscholzia californica Cham. Bright yellow with orange marks on petals Very large UV marks, not coinciding with visual pattern
Plantago media L. Light pink Very weak within the floral parts, some UV reflectance from upper part of stems and spikes


Lysimachia nummularia L. Yellow Weak
Lysimachia punctata L. Yellow None


Anemone blanda Schott & Kotsky Purplish blue Strong UV pattern, high IR reflectance as well
Anemone nemorosa L. White No bull's eye pattern discernible. Quite strong reflectance in near-IR
Anemone ranunculoides L. Deep yellow Strong, indistinct secondary markings on petals
Caltha palustris L. Deep yellow Strong, very large central zone with UV mark. Complex UV fluorescence patterns
Eranthis hyemalis (L.)Salisb. Yellow Intermediate - strong
Hepatica nobilis Schreb. Light blue Very strong UV reflectance (and in near-IR as well)
Ranunculus acris L. Yellow Very prominent bull's-eye pattern, despite only moderate UV reflectance of the flower. A weak two-zoned pattern is present even in near-IR
Ranunculus auricomis L. Yellow Weak, non-descript UV pattern
Ranunculus ficaria L. Bright yellow Very strong bull's pattern in UV, also a similar pattern (but much weaker) found in near-IR
Ranunculus repens L. Yellow Weak - intermediate
Ranunculus reptans L. Yellow Strong, base of petals


Agrimonia eupatoria L. Yellow High UV reflectance of petals, nectaria and styles absorb UV
Comarum palustre L. Dark red or purple  
Fragaria vesca L. White Weak, but detectable
Fragaria vesca L. x viridis Duch. White Interestingly, the UV marks are intermediate to those of the parents
Fragaria viridis Duch. White A bull's eye pattern is present, but not very strongly developed as the outer petals themselves reflect only moderately in UV. The bracts, however, are good UV reflectors
Geum chiloënse Balb. Yellowish red Moderate - strong
Geum urbanum L. Yellow Moderate - strong
Potentilla anserina L. Dark yellow Extremely strong pattern, making this an ideal test object for UV photography
Potentilla atrosanguinea Lodd. Reddish with darker centre Strong, but UV marks are located slightly different from visual clues
Potentilla erecta (L.)Räusch. Yellow Extremely strong, excellent test object. UV fluorescence
Potentilla fruticosa L. Bright yellow None. Petals with negligible UV reflectance
Potentilla intermedia L. Deep yellow Strong, bracts and receptacle show UV fluorescence
Potentilla norvegica L. Light yellow Intermediate - strong
Potentilla recta L. Deep yellow Very strong, prominent UV marks. UV fluorescence of pollen and nectaria
Potentilla reptans L. Deep yellow Very strong and prominent UV marks
Potentilla rupestris L.
(Drymocallis rupestris)
White Weak or intermediate
Rosa dumalis Bechst. Pinkish red Weak, but present
Rosa majalis L. Reddish Weak to intermediate


Digitalis purpurea L. Light red or creamy white Intermediate - strong
Melampyrum pratense L. Yellowish Weak
Linaria vulgaris L. Light yellow None
Verbascum nigrum L. Yellow Intermediate - strong
Verbascum phlomoides L. Yellow Intermediate - strong


Hyoscyamus niger L. Dirty yellow and brown Very strong bull's-eye pattern present, also strong IR reflectance
Solanum dulcamara L. Purple Weak - intermediate, not a typical bull's-eye pattern
Solanum niger L. Whitish  


Viola arvense x tricolor White to yellow, some violet Weak UV reflectance, no clear-cut pattern
Viola odorata L. Violet None, but slight UV reflectance of petals
Viola tricolor L. Tricoloured white, yellow, and violet Weak, more or less coinciding with the visual clues

Note: Some species may have a flower response in the near-infrared (nIR) as well. Few occurrences of this are yet documented, but Ranunculus ficaria might serve as an example. I haven't yet decided whether or not IR aspects should be addressed in these studies. More test shots are needed to assess the potential of adding IR to the study. Since my UV work receives no external funding, I have limits as to the efforts and time which can be spent on documenting these flower features.

All images on these web pages are copyright Bjørn Rørslett - NN/Nærfoto and cannot be used for any purpose, commercial or non-commercial, without express and written approval by the author.

Most uses will incur a negotiable fee. Please e-mail me for details.

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Last Update 24 October, 2006