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Primula vulgaris × P. veris (P.
× polyantha Mill.), False Oxlip

Account Summary

Very rare.

1954; MCM & D; pasture near Roosky Turlough.

April and May.

Growth form, habitats and biology

Primrose (P. vulgaris) and Cowslip (P. veris) usually prefer rather different habitats from one another, but they can occur together in the wild along woodland paths and edges, in clearings and scrub and in hedgerows, 'unimproved' meadows and on roadside verges where the more open ecological conditions exclude neither species. This perennial, rosette-forming Polyanthus is one of the most common of all wild hybrids in B & I and is a very popular garden plant with a wide variety of selected forms. It can arise fairly readily anywhere in the wild that primrose and cowslip occur together.

Experiments show that only the cowslip can act as the seed parent (ie female), the cross providing good seed with up to 37.5% germination. In comparison, when P. vulgaris is the seed parent, only non-viable seed are produced (Valentine 1955). As the cowslip is the more ecologically restricted and less frequent of the two species, the hybrid is rarer than might otherwise be the case and usually represents only 1-2% of any mixed population (Woodell 1965). P. vulgaris flowers much earlier than P. veris, shortening the duration of flowering overlap to some extent. However, both species attract the same range of pollinating insect visitors, despite the flowers emitting distinctly different scents. The hybrid is partially fertile, but markedly less so than both its parents and seed germination is only around 20% (Stace et al. 2015).

In addition to the native F1 hybrid, garden Polyanthus, in a range of flower colours, do occasionally occur as escapes in the wild and have been known to backcross with both their parents. The latter is a rare occurrence and the vast majority of P. × polyantha records in B & I are of F1 crosses between native populations of the two species (Stace et al. 2015).

The F1 hybrid resembles a primrose, but has at least some flowers held at the top of a common stalk like those of the cowslip (Richards 1989). It can easily be distinguished from the rare and local true Oxlip (Primula elatior), which is ± confined to East Anglia, by it having flowers which point in all directions and lacking crisped hairs (Richards 1989). Hybrids are vigorous and regularly form large, long-lived clumps which often are bigger than those of either parent. The hybrid is intermediate in most characters and, although it is fully fertile, back-crossing is rare and only in unusual circumstances of close proximity is there any evidence of introgression (measured in terms of pollen fertility), even when the ecological barriers that normally separate the species are lowered. Thus the two species remain almost entirely distinct as the internal isolating barriers preventing backcrossing and subsequent introgression are strong (Woodell 1965; Richards 1989).

Fermanagh occurrence

This hybrid has been persistent in the Roosky area for over 40 years. It seems to almost always occur where both parents have been established for a considerable number of years. However, on the new roadside embankment of the Enniskillen-Belfast road near Tamlaght, RHN and the current author (RSF) believe less than 15 years elapsed before both parents and their hybrid were discovered. Locally it is found in meadows, scrub and roadside embankments, almost entirely confined to the limestone area SW of Lower Lough Erne.

In Fermanagh, P. × polyantha is present in six lowland tetrads. The full record details are: in rocky pasture between Monea and Drumcose, near the Green Loughs (ie Roosky Turlough), sparingly with both parents, 1954, MCM & D; roadside embankment, 2 km W of Tamlaght, May 1976, RHN & HJN; Caldrum Glebe Td, Caldrum Hill, N of Derrygonnelly, 31 May 1986, I. Rippey; meadow at Beagh Big Td, 25 April 1987, I. Rippey; four plants by Main Drive, Castle Coole estate, Enniskillen, 3 May 1992, RHN & HJN; scrub at Roosky Turlough, 3 May 1993, RHN; Tullynagowan/Beagh Big ASSI meadow, 18 April 1995, RHN & HJN (also 12 April 1997, RHN); twelve plants at knoll, 100 m SE of conifer plantation at Roosky, 12 May 1995, RHN, HJN & B. Morwood; small population by main drive, Castle Coole, 26 April 2005, RHN; persisting here 2010; one plant by track S of Crom Castle near deer enclosure, 29 April 2005, RHN.

In view of the rarity of P. veris (Cowslip) in NI, it is unsurprising that this hybrid is also extremely rare. Apart from the three hectad squares plotted in Fermanagh, the New Atlas map displays just one further square in NI, in Co Armagh (H37). As with P. veris, the hybrid is very much more frequent and widespread in the RoI, than in NI, as is also the case in England and Wales, although becoming rarer and more coastal northwards into E Scotland (Preston et al. 2002).

Threats

Meadow improvements and excessive mowing of verges.