by Sue Leduc
which is the Greek word for 'acrid', is the largest genus in the mustard
family (Brassicaceae, formerly Cruciferae). There are about 350 species
that are primarily native to the northern hemisphere in arctic, sub-arctic,
alpine and sub-alpine regions. Because their natural habitat is so harsh,
they are very good candidates to withstand our extremes of climate.
Members of the Brassicaceae family feature flowers
that are bisexual and whose 4 petals form a cross (+). They have six
stamens, usually 4 longer and 2 shorter. The fruit, called siliques
or silicles, breaks open at maturity to release the seeds (dihiscent).
Draba is a diverse genus of annuals and perennials.
Their forms include cushion, tuft, rosette, carpet, lax carpet, sub-shrub
and erect shrub. Most require a fairly deep root-run, so are not well
suited to growing in a shallow trough.
they bloom in early spring and their flower colour is most commonly
shades of yellow (D. hispanica (bottom of page photo),
D. rigida (photo above), D. aizoides, D. paysonii, D. haynaldii).
White flowers are not rare but they are uncommon (D. glabella, D.
loiseleurii, D. norvegica, D. sakuraii (photo on the left),
D. dedeana). Some are orange-red (D. matthioloides).
There is a Draba for every imaginable combination
of growing conditions in a rock garden: hot, dry and sunny; humousy,
moist and semi-shady; Ca rich and Ca poor soils; and anything in between.
You name it - there is a Draba that will do well. About the
only absolute in cultivating Drabas is that they must be protected
from winter wet.
most frustrating thing about Drabas is that it is very difficult
to identify their individual species correctly. I have a collection
of plants the seeds of which were acquired from entirely reputable sources
that simply are not the species they are supposed to be. I have labels
in the garden that say things like 'not Draba dedeana'
(photo on the right). To compound the frustration, there is very little
written about Drabas. Otto Eugene Schultz wrote a monograph
of the genus in 1927, but I have been unable to find anything more than
passing reference to it in my research. On his excellent website, www.kadel.cz/flora,
Dr. Pavel Slaby has a list of 168 species, most of which have synonyms.
Very few have pictures to help in identification, but all are well described.
All of the Drabas that I have tried have been
the cushion, tuft or rosette forms. They are tiny little evergreen cuties
that bloom from mid-April (the tufts) through to late May (the rosettes).
Some will self-sow quite plentifully (such as D. paysonii)
while others are far more modest. I have found though, that most Drabas
are very easy from seed. The trick is not to sow them so early that
you have to tend the seedlings indoors for too long. They form a large
root mass very early so should not spend too much time confined to a
pot. Many only need 2 to 3 weeks at 20°C to germinate. I have yet
to find any that need any kind of special handling such as cold treatment.
are widely available through rock garden society seed exchanges, though
rather uncommon in the nursery trade. When requesting seed from an exchange
or purchasing seed from a commercial source, be prepared to receive
something other than what you have requested. When your plant has grown
to blooming size and has flowered for you, you will be better able to
determine if it is in fact the species it was purported to be. Better
yet, search out a nursery that offers Draba plants so you can
be sure that it is the form you want. The nursery owner will also be
absolutely certain of the flower colour.
Even the misnamed species are worth having in your garden. Very few
plants bloom as early or as brightly and require so very little care