INTRODUCTION

 Lily breeding was started at the Scottish Horticultural Research Institute (affectionately known as Mylnefield and now incorporated in The Scottish Crops Research Institute) in1966. It began as a suggestion from the director –the late Dr. Colin Cadman. The project met with resistance from the Agricultural Research Council but was eventually written into the Institute’s list of official projects.

     The objective was to produce cultivars suited to the British, and especially the Scottish, climate. I undertook the planning and much of the practical work but had valuable help from Evelyn Wiseman and Barbara Tulloch. My colleague Dr. Tony Wills advised on cytological matters and William Mowatt helped on aspects of testing for virus diseases. The project  was never intended to be a major one and took second place to the main work of the Plant Breeding section where the emphasis was on the breeding of Raspberries, Blackcurrants Strawberries and Brassicas that gave rise to the well known Glen and Ben series of soft fruits and Celtic cabbage. 

     To begin with, varieties and species belonging to the Asiatic group were intercrossed in considerable numbers. The parent plants were grown in pots in a cool greenhouse and, after crossing had been completed, the stigmas of the flowers were covered with tinfoil to prevent further hybridisation by insects and undesirable contact. Seed from the crosses was sown the following spring in a heated greenhouse using plastic washing-up basins with vermiculite kept watered with a soluble complete fertiliser. (003) Vermiculite was employed so that the seedlings could be lifted with minimal root damage and planted directly into the field in May.(004)

    Most of the first batch of some 2,000 seedlings flowered in the year after transplanting and were rigorously selected for vigour, freedom from disease, ability to stand without staking and ease of propagation from bulb scales and four clones were named and released in 1974 These were ‘Orestes’(005,006,007) (outward-facing, orange flowers and many stem bulbils), ‘Odysseus’(009,010) (outward-facing, orange-yellow flowers of heavy texture), ‘Minos’(012,013)(downward-facing, red flowers) and ‘Phoebus’ (014,015)(upright-facing yellow flowers that came rather later than the other three varieties). Later two others were selected; ‘Achilles’ (018,019) and a very short-growing and early-flowering clone (016,017) which was provisionally named as ‘Pandora, but it not certain whether this was ever registered. All of these were multiplied by the bulb scale technique (020) and tested in the field for vigour, ability to stand without staking and apparent resistance to disease.

Lankongense hybrids  Attempts were then made to introduce another species of the Asiatic group into the hybridisation programme. This was L. lankongense (021) – a species from Yunnan province of China bordering on Vietnam. It has true pink flowers of a different colour to others of the group (except perhaps those of  L. amabile ), a pleasant scent and seemed to be somewhat resistant to the troublesome Botrytis  disease. Although Mr. Van de Graaf had described it as a potentially very useful parent, nobody had previously been able to get it to produce hybrids.

     Our first attempts to use it in hybridisation were a failure but it was noted that some of the capsules began to swell after cross pollination  though they did not  give rise to normal seed. which would germinate in soil. The illustration  (022) shows a capsule on L. lankongense resulting from a normal fertile pollination on the left and one from a cross with with another Asiatic species on the right.  The following year some of these partially developed capsules were examined and found to contain a few chaff-like seeds with very small spherical embryos and no endosperm and they would not germinate in soil. Normal viable seeds have much larger sausage-shaped embryos (023) embedded in endosperm.

Some of the very small near-spherical embryos (024) were dissected under sterile conditions and transferred individually to glass tubes (025,026) with a sterile nutrient gel medium. Six of these produced healthy plants which were propagated vegetatively and grown in the field – all were proved by cytological analysis to be true hybrids of  Lilium lankongense x davidii except for one which was a hybrid of that species with an Asiatic cultivar having small dark red flowers. Two were named  ‘Ariadne’ (027,028) and  ‘Adonis’ (029). They were exhibited at an R.H.S. show in London and the latter was the subject of  the Reginald Cory Memorial Cup.

    The following year another greenhouse full of  lankongense first hybrids (including, of course, ‘Ariadne’ and ‘Adonis’ ) was pollinated with various Asiatic hybrids but this time the greenhouse temperature was raised, resulting in many more hybridised capsules producing embryos that could be cultured. Furthermore, it had been noted that many of the plants from cultured embryos died when transferred to compost and to reduce this loss of transplanted embryo plants they were kept in a mist propagator with artificial lighting for a few weeks. These measures resulted in over 300 new seedlings being obtained. Many were vigorous and interesting as can be seen in the illustration of Miss Barbara Tulloch standing amongst them in the field (040) and samples of some of the flowers (041, 042) taken in 1976.

  Once again this second batch of Lankongense hybrids were sterile, producing very little if any fertile pollen. It was therefore decided to attempt to regain fertility by the doubling of chromosome numbers which is a proven method for some wide species crosses. This can be effected rather easily with lilies by treating the bulb scales with a dilute solution of colchicine when many of the bulbils thus produced will be polyploids. With very few exceptions, wild lily species and most cultivars are diploids with 24 chromosomes and when these are treated with colchicine they give rise to a number of plants which are tetraploids having 48 chromosomes. The tetraploids usually bloom  somewhat later and have  flowers with broader petals (strictly ‘tepals’ for there is no clear difference between petals and sepals in Lilium). This is demonstrated in illustration  (038) showing diploid flowers of ‘Orestes’on the left and tetraploid on the right. From (039) it can be seen that  stamens of the tetraploid form of the species cross ‘Ariadne’ produce copious pollen whilst those of the diploid form have little if any fertile pollen. It was therefore decided to double the chromosome numbers of ‘Theseus’, ‘Eros’ and ‘Pan’. When this was done a chromosome count showed that many had, in fact, 72 chromosomes indicating that the selections we had been looking at were in fact triploids with 36 chromosomes. This was of special interest for the few triploids known amongst lilies are especially vigorous and often especially adaptable. The best example of these in the tiger lily said to be a wild species Lilium lancifolium  which is, in fact, a hybrid with three sets of chromosomes, one set being different from the others – it is therefore technically described as an allotriploid as distinct from an autotriploid which has three identical sets of chromosomes. It would seem that allotriploidy is something to be aimed for in lily cultivars though these have the disadvantage of being more or less sterile.

The So-called North Lilies     The second batch of Lankongense backcross hybrids were very promising and most were propagated vegetatively and grown on a reasonable scale in the field. All of those chosen were found to be triploids, the diploids were invariably weaker growers. Ten of the best were chosen for vigour and apparent disease resistance and to include a wide range of flower colour – all had downward-facing flowers. These were eventually sold by the Institute to the Lily Group of the R.H.S. in1986. At their request I gave names of female members of the North family ranging from my step-mother to nieces. They are figured here; ‘Angela’ (550/6) in 1977  (043, 044);  ‘Barbara’ (523/1) in1977  (045,046), ‘Bronwen’ (556/3) in 1980  (047), ‘Helen’ (523/3) in 1987  (048), ‘Eileen’ (544/1) in 1978 (049,050), ‘Marie’ (505/2) in 1980 ( 051,052,053), ‘Hannah’ (510/21) in 1978 and 1980 (054,055), ‘Karen’ (531/7) in 1980 (056), ‘Peggy (510/2) in 1980  (057), and ‘Rosemary’ (510/5) in 1980 and 1978  (058,059). A list of names was given to the Lily Group and the only one chosen by the nominee was ‘Marie’ my wife which, although it is appropriately a rather beautiful and unusual coloured flower it is, quite uncharacteristically not one of the best ‘doers’.

    The black, bracketed numbers refer to the cross made and the individual  seedling selected. Thus ‘Peggy’ and ‘Rosemary’ came from the same cross (not the nominees!). In addition to the ten quoted above, a number of unnamed selections were sent to Wisley and these have now been passed on to members of the Lily Group. They include:-

              060   500/1           069     523/3             078     531/5

              061   507/1           070     523/4             079     543/23

              062   507/2           071     525/3             080     543/23

              063   510/2           072     528/4             081     551/1

              064   507/2           073     527/1

              065   510/2           074     550/1

              066   510/10         075     518/1

              067   510/20         076     523/5

              068   514/3           077     528/1          

These details are included in case any members of the Lily Group have these clones labelled under the numbers.

 Euro/Caucasian hybrids   This term was used for crosses between Lilium pyrenaicum  and similar species found in the Alpes Maritimes, North East Turkey, the Caucasus and Iran. Generally they are long-lived species that persist in Scottish gardens. L. pyrenaicum itself occurs wild in places and is very persistent, even when growing in turf. However, few if any hybrids within this group are known.

    All pollinations were made on plants of L. pyrenaicum growing in the open at a nursery in Perth by courtesy of the proprietor Mr. Jim Aitken. Pollen was mostly obtained from   specimens in a heated greenhouse at Mylnefield  since it had to be obtained at the right time for use on the mother parent that flowers earlier than other species. The hybrid seed was grown by embryo culture as with the Lankongense material for the crosses resulted in imperfect seeds though some of the had moderately sized embryos but deficient endosperm. Another advantage of endosperm culture was that the small embryos grew without delay and had no dormancy period characteristic of this group of species.

     Most of the crosses resulted in hybrid flowering plants including pyrenaicum x monadelphum  (082,083); pyr.x ponticum  (084,085); pyr. x ciliatum  (087,088); pyr x chalcedonicum  (089,090); pyr. x pomponium (091,092,093,094).  The hybrids were generally intermediate between the two species envolved and were multiplied vegetatively and grown in the field. Surprisingly they mostly did not seem to be very vigorous or persistent growers and were discarded. However, the cross with pomponium grew well and was considered to be worthy of releasing as a new variety as ‘Europa’ but this name had to be abandoned for it was already used in the Lily Register for another cultivar. Through the encouragement of Mrs. Dee Simmons it was agreed to call it ‘Christopher North’ or ‘Chris North’. To mollify my embarassement I have to state that my father’s name was Christopher, one of my grandsons living in the U.S.A. has this name and so also has one of my nephews.

     One other clone was retained that came from the cross Lilium pyrenaicum x ciliatum and figures in (087,088). It is very similar to pyrenaicum and grows well in grass in my garden where it , surprisingly , sets seed fairly regularly.

Lilium henryi hybrid.     The final aspect of the work at Mylnefield was to use the expertise gained in embryo culture to try and provide a cross between Lilium henryi  and one of the Asiatic hybrids. This lily species has been crossed with the trumpet lilies such as L.sargentiae giving rise to the successful group of Aurelean hybrids and with the Oriental group to give ‘Black Beauty’ and it might be useful to hybridise it with a member of the very popular Asiatic group.

    A greenhouse full of L. henryi was pollinated with several members of the Asiatic group and six seedlings were obtained using embryo culture. Five of these had relatively broad leaves like those of the mother parent but one had narrow leaves  (095). Since one can not be sure with some inter-species pollinations whether they are true hybrids or apomictic ( arising solely from the mother parent) all were examined cytologically. (see 111) Only the narrow-leaved seedling was a true hybrid of henryi x Asiatic cultivar and the first ever to be recorded. It flowered well in the greenhouse (600/1)( 096,097), propagated easily from bulb scales and multiplied substantially in the field. Unfortunately, but a very rare mistake in the records one can only say that the pollen parent was certainly an Asiatic cultivar (confirmed from chromosome analysis) but which one is uncertain. It was probably an unnamed cultivar received from Russia.

     I would liked to have released this clone under the name of Eureka but, although it grew and flowered well, it did not seem to be up to the standard of the previous Mylnefield cultivars to credit this distinction. It could be a useful bridge for breeders and some bulbs were made available to members of the lily group but I know of no sources at the present.

Chromosome illustrations  From time to time the chromosome content of plants used in breeding were examined. This was done by root tip squashes viewed under the microscope. Cells which happened to be dividing were examined and in some cases the morphology of the chromosomes was recorded by ‘camera lucida’. This is a simple apparatus which projects a virtual image on to a piece of paper and one can draw the outline of chromosomes. A few of such drawings are depicted in 106-111. The basic (aneuploid) number of chromosomes of egg cells and pollen in all Lilium species is 12 though occasionally one or two extra chromosomes  may be found in some forms. The usual body cell therefore is diploid with 24 chromosomes. This can be seen for one of the early Asiatic hybrids bred at Mylnefield in 106 and for the species Lilium lankongense in 107. This is also the case with the first L. lankongense diploid hybrids of which only two were released – ‘Ariadne’ and ‘Adonis’ (see 108 ). Very few wild species of lilium are triploid with 36 chromosomes but the tiger lily Lilium lancifolium (if it really is a true species and not a naturally occurring inter-specific hybrid) is an example as can be seen in 109. However one of the reputed hybrids of it ‘Wiltig’ is evidently a diploid (see 110 ). Unfortunately no camera lucida drawings were done of the other L. lankongense hybrids that were released – they are all triploids.

     Chromosome drawings can also be used in some cases to find whether putative hybrids really are true hybrids and this was done with 600/1. The illustration 111 shows the chromosomes of Lilium henryi (the complete diploid set and the haploid set of 12 below). The following drawing 112 of the chromosomes of 600/1 shows at least one chromosome that is not from L. henryi but an Asiatic hybrid.

     The last two inclusions  (104, 105) are taken from Mylnefield records of the crossings which gave rise to the batch of plants from which the so-called North lilies were selected. (the 505 series).

       Column A refers to the family from which the clones were selected.

                     B  the cross of the or original F1 Lilium lankongense  hybrid (230 series of

                     which ‘Ariadne’is 230/13 ) is the female parent and an Asiatic type the pollen     

                     parent. Sometimes the latter was an established cultivar such as ‘Enchantment’,

                    ‘Destiny’or ‘Redbird’ but mostly an unnamed hybred at Mylnefield.

                     C   The record of embryos excised and added to tubes of nutrient. – black

                     transferred to compost December 1973, yellow January 1974 and red February

                     1974. Where an oblique line is drawn through indicates that the plantlet died

                     after  transferring to compost.

                     D. Records the ploidy from cytological analysis of those plants examined.

                     d=diploid  and t= triploid.

From these records it may be possible to find the parentage of some of the 500 series clones.. For example ‘Bronwen’ (556/3) is a cross with ‘Destiny’, ‘Hannah’ with ‘Enchantment’ and so are ‘Peggy’and ‘Rosemary’.

Commercialisation.  Now matter how good a plant variety is, it is unlikely to be a success unless it is well advertised and made available commercially. The Mylnefield lilies have certainly been well advertised but the commercial production has not yet come up to expec tations. The early crosses were grown and sold by Highland Liliums and my colleague Dr Peter Waister has done a first class job obtaining and maintaining virus free stocks of the North lilies owned by the Lily Group, but their commercialisation is at present somewhat in the doldrums. It is hoped that this position will soon be solved.

       All the photographs on this Cdrom were taken by myself and I accept full responsibility for any errors or mistakes. If viewers have any comments or suggestions please let me know at:     Newmill of Knapp, Inchture, Perthshire PH14 9SW                                  

Chris North                                                                                               24 November 2000