two Onosma species need identification

[TheOnionMan]

From NARGS Seedex several years back, labelled Onosma nana, came a rather tall Onosma, about 30-40 cm, very bristly irritating foliage, and large luminous pale yellow flowers.  Showy, but definitely not O. nana, the true species supposed to have white flowers tinged pink or blue, and red stems and calyxes, and of course, short stems.

The second is an Onosma species from Turkey.  The silver leaves are not bristly, stems tend to be decumbent, to about 20-25 cm tall, narrower bright yellow flowers.

[Lesley Cox]

I haven't a clue really, but what about O. flavum? and that has a cultivar form as 'Golden Drop' which was around here many years ago.

[Heather Smith]

The Onosma species found in the Pyrenees is known as "Pyrenaean Golden Drop" (O. bubanii) and I would love to get it. It is to date the only Onosma I have seen in the wild.

[TheOnionMan]

I haven't a clue really, but what about O. flavum? and that has a cultivar form as 'Golden Drop' which was around here many years ago.

Thanks for the suggestion.  I see Onosma flavum listed in Reginald Farrer's The English Rock Garden, although I don't think that is a recognized species name based on my searching and it is not listed in the International Plant Names Index (IPNI), although there is  O. flava and O. flavida listed.   Searching http://www.ipni.org/ipni/plantnamesearchpage.do and inputting "Onosma" and "*" for the species name comes up with 438 names!  Onosma is a big genus, with most of those having yellow flowers.

The name 'Golden Drop' also doesn't come up with much except that it seems to be a common name for yellow Onosma species in general.  Reginald Farrer writes about O. tauricum "Our well-beloved favourite old Onosma, the one and only Golden Drop of the garden", and goes on to say "gracious croziers of hanging ample flowers of a waxy and lemony lusciousness peculiar to themselves, and exactly asking for the name of Golden Drop in their melting confectionery clarity of colour and texture".  (he sure could pile it on )
 
So, after looking around more, it is likely that my plant is one of the commonly grown Onosma species, such as echioides, stellulata, helveticum, or indeed, tauricum.  I need to take a closer look at each of these species descriptions to see if I can find a match.  The foliage on helveticum is described as bristly, so at least that aspect matches, but many Onosma are bristly.

[TheOnionMan]

The Onosma species found in the Pyrenees is known as "Pyrenaean Golden Drop" (O. bubanii) and I would love to get it. It is to date the only Onosma I have seen in the wild.

Thanks Heather, I had never heard of this species, and apparently it is well known as "Pyrenaean Golden Drop".  Harder still to find a good photograph, but I did find some:  http://www.lafloredespyrenees.fr/boraginacgenres/onosmabub/onos2.html
It is a lovely Onosma, and soft moonlight yellow flowers as mine is. 

For comparison purposes, I have cropped a closeup flower crozier of my unknown "Onosma sp.", showing a similarly sized crozier of Onosma stellulata (seems to be the correct spelling, versus stellulatum?).  Similar, flowers, but stellulata has distinct green leaf-like bracts in the unfurling crozier, not seen in my plant.  The flower shape and calyx lobe segments look similar in both.  Then I also made the same comparison with my "sp" and O. bubanii from the web image, but flipped to face the same direction.  Again rather similar, but the calyx segments look much longer against the flower in O. bubanii.

[Lesley Cox]

Yeah, sorry, it was O. tauricum that had a "golden Drop' form, not O. flavum.

[Lesley Cox]

Onosma flava should correctly be O. flavum, a masculine or neutral ending to match the Greek ma of Onosma, like Arisaema (speciosum etc), Aethionema (pulchellum etc).