This spring has been a good one for the shrub colloquially known as yesterday-today-tomorrow bush (Brunfelsia australis/latifolia), which are showing off their multicoloured flowers profusely at the moment. This is a great shrub for Sydney gardens, growing to around 2 m tall with glossy green foliage. It comes into bloom around September and continues into October. Its simple, scented flowers open violet in colour, then change to pale blue and then white. The variety of colours on the bush at the one time gives an attractive effect. I recently acquired one from the Friends Nursery at the Royal Botanic Garden that has really large leaves and flowers (possibly Brunfelsia pauciflora 'Macrantha'). Another species, Brunfelsia americana, has white flowers that age to yellow. I do also have one of these, but it is a very slow grower and it has not yet flowered for me.
I began to think of other flowers that also change over time in this way - and to ponder: 'Why?' The marmalade bush (Streptosolen jamesonii, ht 1.5-2 m) is another easy-to-grow shrub for Sydney gardens that is in full bloom now, and it has flared-trumpet flowers that change from yellow through clear apricot to a deep orange-red as each opens then matures. Research suggests that this change may allow insect pollinators to accurately estimate the age and possible nectar content of the flower, benefiting both the plant and the insect. A similar process is thought to operate in the case of Brunfelsia flowers.
Where bees are the primary pollinator, the colour of the just-opened flower is often in the purple and blue range of hues - which bees are highly attracted to. The herb borage (Borago officinalis) for example, has new flowers that are bright blue and that fade to a lavender pink color once seeds have begun to form.
Flowers that have the species or cultivar name mutabilis or mutabile (meaning 'changeable' in Latin) usually show this colour-changing phenomenon. The spring-flowering perennial wallflower Erysimum mutabile (ht 1 m), from the Canary Islands and Madeira, and which does well in a dry, sunny spot in Sydney gardens, opens pale yellow and ages to purple. Another lovely plant is Nicotiana mutabilis, an annual or short-lived perennial plant for a sunny spot. It has a large soft rosette of basal leaves, and through much of the year, it sends up branched spires (ht 1-1.3 m) of pretty funnel-shaped flowers which change colour from white, to pale pink to rose pink as they age, giving a billowing, multicoloured effect that remind me of a packet of pastel marshmallows.
The rose of Sharon or confederate rose (Hibiscus mutabilis, ht to 3.5 m) is a shrub or small deciduous tree that grows reasonably well in Sydney gardens. The large single or double flowers appear in autumn and open white and age from pale pink to deep pink. The well-known China rose 'Mutabilis' (ht 2.4 m - to 5 m as a climber) is a popular plant in Sydney gardens as it flowers for so long and is robust in our climate. Its stunning single flowers open light yellow then change to copper-pink and then to deep pink.
Some of our native Chamelaucium have flowers that change colour from white to red, including C. ciliatum and C. megalopetalum. All 'kaleidoscope' flowers offer good opportunities for gardeners to create planting combinations with them of other blooms or leaves that echo one or more of the colours of the flowers as they age. I have been contemplating planting some purple, white and mauve violets underneath my yesterday-today-tomorrow shrub, for example! I have also sown some borage seeds in an area that has blue and pink flowers. I'd love to hear from readers any other examples of these sorts of blooms!
Tall summer volunteers
24 Jan 21
These will provide colour and form in your garden every summer.
A neon rainbow revisited
17 Jan 21
Hot-coloured flowers still feature in my summer garden
The zucchini files
10 Jan 21
Zucchini can be a rewarding summer crop.
Random musings on a walk
03 Jan 21
Lots of plants caught my eye on a walk.
13 Dec 20
Cut flowers for Christmas vases