How Many days does a flower of Phacelia parryi, Parry's phacelia, Last?
A single plant of Phacelia parryi came up in my Fallbrook yard in early 2023, probably a seed that remained ungerminated from ones I spread in my yard in late 2017 from Lee Gordon, or a seed that came from one of the plants that bloomed in early 2018. If so, this seed waited either five years before germinating in the first case, or four years in the second case, with no other plants seen in the intervening four years. However, it is remotely possible that this was a natural introduction to my yard, since this species grows wild all around Fallbrook.
In order to find out how long an individual flower lasts, I photographed the flowers each day for a period of 14 days, missing only a single day.
I call Day 1 the first day in which each individual flower is open for the first time.
The buds swell the day before they open, and open either on the evening before their Day 1, or the morning of Day 1. See the bud for the second flower to open on this plant in the morning while the first flower is still blooming, and its open flower on the evening of that same day (the flower in the background while the first flower is still blooming).
Figs. 1 and 2 show repeat photographs of the first and second flower to open on this plant. The second flower opened two days after the first flower, so its "Day 1" is the same as the first flower's "Day 3".
The corollas for each of those two flowers are fresh-looking on days 1 to 3, but are clearly in decline on days 4 and 5. The declining corolla remained on the plant until day 8 or 9 for the first flower, and day 7 or 8 for the second flower. The corolla of the first flower fell from the plant on day 9 or 10, and the corolla of the second flower fell from the plant on day 7 or 8.
| Day 1 | Day 2 | Day 3 | Day 4 |
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| Day 5 | Day 6 | Day 7 | Day 8 |
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| Fig. 1. Photographs of the same flower, the first one to open on this plant, on successive days. No pix were taken on Day 9; on Day 10 the corolla had fallen | |||
| Day 1 | Day 2 | Day 3 | Day 4 |
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| Day 5 | Day 6 | Day 7 | Day 8 |
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| (No pix taken) | 
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| Fig. 2. Photographs of the same flower, the second one to open on this plant, on successive days, where Day 1 is the first day in which this flower was open. | |||
I thank Lee Gordon for sending me seeds of P. parryi back in late 2017, which may have made this study possible.