Hieracium murorum [Wall Hawkweed]

[Andrea B.]

Blum, A. G. (2015) Hieracium murorum L. (Asteraceae) Wall Hawkweed. Flowers photographed in ultraviolet and visible light. http://www.ultraviol...-wall-hawkweed/

 

Causeway Lane, Southwest Harbor, Maine, USA

07 & 19 July 2014

Blagden Preserve, Mount Desert Island, Maine, USA

29 July 2014

Wildflower

 

Synonyms:

• Hieracium hyparcticum (Almquist) Elfstraud
  
• H. lividorubens (Almquist) Zahn
  
• H. stelechodes Omang
  

Comment:

The chief characteristics distinguishing H. murorum from H. kalmii or H. scabrum are the almost leafless stems and the persistent basal rosette. The blunt leaf base on a rosette leaf distinguishes H. murorum from H. lachenalii.

 

Reference:

1. New England Wild Flower Society (2015) Hieracium murorum L. Wall Hawkweed. https://gobotany.new...racium/murorum/

 

Equipment [Nikon D600-broadband + Carl Zeiss 60mm f/4.0 UV-Planar]

Unless otherwise noted.

 

Visible Light [f/9 for 1/800" @ ISO-800 with Nikon Df + Nikon 60mm f/2.8G Micro-Nikkor]

H. murorum capitula. Note stipitate glands on involucre.

 

Visible Light [f/9 for 1/100" @ ISO-800 with Nikon Df + Nikon 60mm f/2.8G Micro-Nikkor]

H. murorum plant growing near fir.

 

Visible Light [f/8 for 1/30" @ ISO-400 with Nikon Df + Nikon 60mm f/2.8G Micro-Nikkor]

Young colony of H. murorum plants.

 

Visible Light [f/9 for 1/1250" @ ISO-800 with Nikon Df + Nikon 60mm f/2.8G Micro-Nikkor]

Basal rosette remains present during the plant's life.

 

Visible Light [f/9 for 1/640" @ ISO-800 with Nikon Df + Nikon 60mm f/2.8G Micro-Nikkor]

Stipitate glands on stem.

 

Visible Light [f/11 for 2.5" @ ISO-100 with onboard Flash and Baader UVIR-Block Filter]

Leaf close-up showing sparse hairs.

 

Visible Light [f/11 for 2.5" @ ISO-100 with onboard Flash and Baader UVIR-Block Filter]

Leaf close-up showing hairs along edge.

 

Ultraviolet Light [f/11 for 15" @ ISO-400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]

A newly opened flower from a young plant.

 

Ultraviolet Light [f/11 for 15" @ ISO-400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]

A larger flower from a more mature plant.

 

Ultraviolet Light [f/11 for 20" @ ISO-400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]

Abaxial view.

 

 

FNA | Family List | FNA Vol. 19, 20 and 21 | Asteraceae | Hieracium

25. Hieracium murorum Linnaeus, Sp. Pl. 2: 802. 1753.

Plants: 25–60+ cm.

Stems: proximally piloso-hirsute (hairs 1–3+ mm), distally stellate-pubescent and stipitate-glandular.

Leaves: basal 3–6, cauline (0–)2–3+; blades (often purple-mottled) ± elliptic, 50–110 × 25–45 mm, lengths 1.5–3 times widths, bases rounded to truncate, margins ± dentate, apices ± obtuse (apiculate), abaxial faces piloso-hirsute (hairs 1–3+ mm), adaxial scabrous to piloso-hirsute (hairs 0.5–3 mm).

Heads: 5–8+ in corymbiform arrays.

Peduncles: densely stellate-pubescent and stipitate-glandular.

Calyculi: bractlets 8–13+.

Involucres: campanulate to obconic, 8–9 mm.

Phyllaries: 18–21+, apices ± acuminate, abaxial faces stellate-pubescent and stipitate-glandular.

Florets: 30–50+;

Corollas: yellow, 12–13(–16) mm.

Cypselae: columnar, 2.5–3 mm; pappi of 30–40+, stramineous bristles in ± 2 series, 4–5 mm.

Flowering: Jun. Disturbed sites (fields, openings in woods), thickets; introduced; 0–100+ m;

B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., Que.; Alaska, Conn., Ill., Maine, Mass., Mich., N.H., N.J., N.Y., Pa., Vt.; Europe.

[Damon]

Hairy one there. Some great full sun it looks like.

Very sharp photos. gonna get me one of those planars someday...

I noticed you switched lenses according to your info. there. Says Planar then Nikkor. Or you meant something else.

 

-D

[Andrea B.]

I was using the Df + 60/2.8 for the visible ID shots made on location when I first find the plant. These Hieracium are so darned difficult to ID that I try to get photos of everything - leaves, stems, buds, flowers, area where growing and so forth.

For the indoor close-ups I used the UV gear.

[nfoto]

In Europe, Hieracium has been abandoned by virtually all people. Even the overzealous taxonomists eager to put their names on a new 'species' no longer can penetrate the chaos they, with generous help of Nature, have created.

[Andrea B.]

I think it might perhaps be useful to note that the Hieracium I am able to ID are all seen on an island, Mount Desert Island. It is possible that this provides somewhat of an isolated environment. This is not to say that there aren't some Hieracium there which appear to have drifted from the type.

 

I stick very much to Arthur Haines' Flora Novae-Angliae key. If a Hieracium does not fit the type there, then I'm not going to post it here. And while I agree that this is no guarantee of a perfect ID being made, I think I'm at least in the ballpark most of the time. (In Maine the favorite ball park would Fenway in Boston, home of the Red Sox.)

 

I look at stems, leaves (ab&ad), habitat, involucres, cypselae, peduncles, trichomes. I count & measure the rays, measure the involucres, measure the seeds, count stem leaves, estimate plant height, dig for stolons & rhizomes. I check for glandular, branched or stellate hairs with a magnifying glass.

It is enjoyable. I've learned a lot.

 

H. murorum is a fairly easy ID. Of the non-Pilosella-type Hieracium having persistent, obvious basal rosettes, only two on the island have 'plain' leaves, not mottled/blotched. If the rosette leaves have a blunt base, then Wall Hawkweed. If not, then Common Hawkweed.

 

And so forth. :D