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Cambridge University Botanics Mountain Plants Diary

This entry: March 2013 - Lengthening days by Helen Seal and Simon Wallis

Here we are at the end of March and it still feels like winter, but the lengthening days have nevertheless triggered many of our plants into spring action. New leaves are emerging on the crowns of the herbaceous mountain plants which looked like stumps of dead twigs all winter. The leaves of some cushion plants die but remain attached as an insulation layer for the winter and we wait anxiously for the new growths to appear. In the Mountain House’s landscaped bed the Draba mollissima seems lifeless every winter, but appearance is deceptive, and fresh green leaves begin to cover the old.

Draba mollissima - the first signs of the new seas

Draba mollissima - the first signs of the new seas

However, the x Leucoraoulia loganii is probably no longer just looking dead, I think it actually is.

A dead x Leucoraoulia loganii

A dead x Leucoraoulia loganii

At this time of year, the Alpine section is busy with some of the Garden’s National Collections; we tend the Tulipa species, the European Fritillaria, Saxifraga and Alchemilla. First to flower are the tulips. These used to be planted in lattice pond pots and plunged into different beds outside in the Garden each year to avoid the build up of fungal diseases like tulip fire. The pots were lifted once the foliage had died down, the tulips extracted, dried on racks, cleaned, with the old, loose, papery outer layers removed along with any diseased material, and then stored in onion sacks ready for replanting in the autumn. This all took quite a long time, and great care had to be taken that no tulip bulbs escaped unnoticed from the lattice pots resulting in random, unlabelled plants. And of course the labels had to stay with the correct bulbs. We are now taking a different approach:  the tulips are grown in clay pots, plunged in sand beds in the Alpine Yard and brought into the Mountain House when in bud.  The tulips are repotted every second year and this new system seems to be working well.

It is surprising how long tulips can persist without the stock developing viruses (which would be evident by short yellowish streaking in the leaves). This Tulipa humilis came to the garden in 1976 and is still flourishing. One of the benefits of keeping a National Collection is the accumulation of records. For example, we can track the cycles of increase and decline in bulb numbers. In 1982 the garden had 22 flowering sized bulbs of this Tulipa humilis stock, only 7 in 1996, but 52 by 2009.

One of the pots of the 1976 Tulipa humilis

One of the pots of the 1976 Tulipa humilis

Many species of tulip are variable, and here in T. humilis the petal colour ranges between the magenta of the 1976 stock and the rose of the 1994.

The 1994 pot of Tulpia humilis

The 1994 pot of Tulpia humilis

Two stocks of Tulipa biflora differ in form: those of 1999 are delicate and slender, with subtle grey colouration on the outer tepals; those of 2008 are robust and broad. Although we commonly talk of tulip flowers having petals, technically they are tepals. Botanists use this term when it is unclear what is a petal and what a sepal – these are the floral segments that protect the flower bud.

The 1999 pot of Tulipa biflora

The 1999 pot of Tulipa biflora

The 2008 pot of Tulipa biflora

The 2008 pot of Tulipa biflora

These Tulipa schrenkii are recent acquisitions from different sources, but one shows distinctive green feathering on the tepals.

The green feathering on the tepals of Tulipa schre

The green feathering on the tepals of Tulipa schre

A Tulipa schrenkii with less green feathering to t

A Tulipa schrenkii with less green feathering to t

This enormous pot of Tulipa kaufmanniana flowers abundantly every year and came from a bulb merchant back in 1989. We are now growing on bulbs from seed from different habitats in Kazakstan and expect to see far more variation when these reach flowering size in a couple of years.

A pot Tulipa kaufmanniana bursting with flowers

A pot Tulipa kaufmanniana bursting with flowers

We have arranged the tulips on display by botanical sections, which differ from those used in horticultural bulb catalogues – these list mostly named cultivars rather than species. Some of the features used to distinguish these sections are not immediately obvious, but the Biflores group is easily recognised since each stem bears more than one flower (sometimes three, or even four, not just two as the prefix “bi” suggests).

Not all differences between plant specimens with the same name are due to variation however. These two labelled Iris vicaria (which even bear the same record number), differ because the yellow-flowered one is an imposter, not Iris vicaria at all but another juno iris! We are busy trying to discover which.

Iris vicaria

Iris vicaria

The unknown imposter

The unknown imposter

Sometimes the differences could be due to where the plant is grown. The European Saxifraga have yet to flower, but one with a wonderfully long name for a small plant, Saxifraga federici-augusti ssp grisenbachii is both pot grown and in the Rock Garden. We often find that plants in the Rock Garden are further advanced than those in pots. In this case the typical red colouration of the elongating stems just shows that the outside plant is experiencing spring earlier than its indoor counterpart.

One of our Saxifraga federici-augusti ssp grisenba

One of our Saxifraga federici-augusti ssp grisenba

Saxifraga federici-augusti ssp grisenbachii growin

Saxifraga federici-augusti ssp grisenbachii growin

The garden’s website has more information about the National Collections

www.botanic.cam.ac.uk/the garden/collections /National Plant Collections

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