In Search of the Golden Fleece

 Allan Robinson, UK

Our family Nursery had grown a good number of Erodiums for decades and E. chrysanthum had been a distinct and popular item since WW2, probably before. Propagation was generally done either by top or root cuttings although some species could only be multiplied by seed. Erodium chrysanthum was never a problem from either form of cutting, but seed was not produced as all the plants in cultivation were male. In fact, all the Erodium chrysanthum in cultivation were a single clone.

The Genus Erodium is mainly centred on the Mediterranean Basin; Spanish and French mountains host a huge number of species as do those of Morocco. Moving eastwards we find E. chrysanthum in Southern and Central Greece and the beginning of Erodiums becoming dioecious, the term for species that produce separate male and female plants. This characteristic becomes more normal as Erodiums move into Turkey and beyond.  

In the early eighties I went to visit Marshall Olbrich at his famous Western Hills Nursery in Northern California. I was whisked around nurseries and gardens in the San Francisco area and in one garden, at Lafayette there was a plant that kindled my further interest and curiosity in Erodium chrysanthum.

This Californian Erodium had darkish green leaves and flowers of a real golden colour, it was quite stunning. On close scrutiny it was pronounced “Female”! My excitement was soon quashed when I was not allowed to have a cutting to take home. I was told some time later that the plant had died and as nobody had been allowed any propagation material it was lost to cultivation. On reflection, it was a good thing the plant remained in that garden as further investigation would probably have ceased, thinking that the elusive female had been discovered. I have since heard of other similar plants being grown in California.

Conversations around the campfire in California and back in England seemed to give credence to the fact that female forms have green leaves and golden flowers whereas males have pale flowers and greyer leaves. The mystery deepened.

It should be remembered that Latin is quite precise when dealing with colour and “chrysanthum” means golden. There are many other words to describe shades of yellow, such as aurantiacus, flavus, luteus and sulphureus, to mention a few.

So, in the late nineteen nineties our quest to find wild Erodium chrysanthum was launched. Although regularly visiting Greece we would now have a focus for our holiday. We had done what homework we could as to where it grew in Greece, a few mountains in the Peloponnese and Central Greece appeared to be its’ home. We started looking in the Northern Peloponnese and three trips later we still had not found it. The fourth year we went south to the Central Peloponnese and found a colony at 1400 metres. A huge sigh of relief echoed across the mountainside. It was 2007 before a small colony revealed itself in the Northern Peloponnese, about one hundred metres above the upper vestiges of Geranium subcaulescens, at around 2100 metres.

The lower colony was found growing on a flattish area where some limestone was visible and the soil seemed to be a sandy loam. In contrast, the higher population was growing in a steep limestone scree which was very difficult to stand on without discovering gravity. The one common factor is the presence of limestone as the majority of species require a high pH or alkaline soil.

Having found two colonies in fairly different environments, we have come to a few early conclusions. I’m sure there is still a great deal to learn about this species, especially regarding its’ close relatives. Another yellow flowered species, E. hartvigianum, has been recently discovered in the north of Greece and due east in the most western area of the Turkish mainland is Erodium somanum, again a yellow. Perhaps, when the Mediterranean and Aegean seas dried up an aeon ago, a yellow flowered ancestor grew over a much larger area, only to be reduced and isolated when the water returned.

Studying our two E. chrysanthum sites there are three discoveries worth mentioning.

First is the lack of dark green leaved forms in the wild. Plants vary from having greyish-green to good silver leaves; some of these could be grown for their foliage alone. On initial viewing, there does seem to be a tendency for male and female plants to display distinctive foliage. As we begin to understand this characteristic, hopefully seed raised plants can be sexed without flowering.

Secondly, flower size in wild populations is slightly smaller than many Erodiums including the chrysanthum in cultivation.

The third point is anther / pollen colour or the lack of it. The wild plants that we have seen do not produce coloured pollen, but is whitish and not at all prominent, whereas the commercial form displays  distinct colour in its’ anthers / pollen. See the accompanying photograph which allows a comparison of wild and commercial Erodium chrysanthum, although the colour has been diluted somewhat during the photographic process. Remember chrysanthum means “golden flowered” in this instance.

It would seem that the E. chrysanthum grown and sold in the UK for at least half a century is actually a hybrid, probably belonging to the E. x lindavicum group of hybrids. This group can vary from whitish flowers to paler shades of yellow, apricot and pink. The original cross was made by the famous German nurseryman, Franz Sündermann at Lindau by Bodensee (Lake Constance) in Southern Germany. He hybridised E. chrysanthum with E. absinthoides to obtain the first Erodium x lindavicum. No doubt today, the parentage of many plants thought to be in this group, is far more complicated if propagation has been continually done by seed.

Although they are very desirable, the dark green leaved plants still resident in California should also be regarded as hybrids. Not only are the leaves un-characteristic with the species but also the stature of these plants tends to be far too large for Erodium chrysanthum. Hopefully someone will return to these shores with some samples of these wonderful plants in the near future.

Our investigation will continue to try and understand this elusive species which has been totally ignored by taxonomists for so long, especially in the UK. Already we have a hybrid between wild E. chrysanthum and our E. guicciardii which displays amazing silvery leaves. This is just the beginning of a new generation of hybrids based on true Erodium chrysanthum.

Allan Robinson, Sutton Bridge, 12th September 2010

Here is a comparison of some Erodium chrysanthum flowers. The two pale blooms in the centre are from the form of Erodium chrysanthum sold in the horticultural trade. The deeper yellow flowers on either side are from typical Central Peloponnese forms, female to the left, male to the right.The top two male flowers are one clone, the bottom right is a second one. It is worth noting the difference between the anthers/stamens and pollen colour on the Horticultural form and those belonging to the wild types. 

Photo  Allan Robinson

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