If you want to see flowers of Tragopogen pratensis in bloom, you will need to look for them before lunch because it lives up to one of its common names Jack-go-to-bed-at-noon. Whatever the weather, flowers of this common member of the dandelion family close by midday. It's one of a number of species whose floral movements can be used as a primitive clock. Scarlet pimpernel opens and closes depending on temperature and humidity change, but finally closes for the day at about 3 pm, rain or shine. The gardening writer JC Londou in 1872, planned floral clocks constructed from species with this kind of behaviour, claiming floral opening and closing times to an accuracy of minutes. Though they have fairly predictable opening and closing times, their time keeping ability would have been constantly disrupted by variable weather. And so it is not surprising _______.
A. that Londou's clock was popular in the 19th century
B. that Londou's clock can be seen only in horticulture gardens
C. that Londou's erratic botonical time piece never caught on
D. that Londou's clocks are among the most accurate of primitive clocks
E. that Londou is highly respected by botanists