Well, talk about going down the rabbit hole. I decided to try to satisfy my curiosity about flowers and nectar and how often they produce/replenish their nectar, and I fell in to a huge amount of information. A fascinating time-suck. This sort of internet-information gathering always makes me think of this:
How lucky we are to live in the time of instant information. (And also, maybe, cursed.)
Anyway, from all the reading I have just done, I have learned that flowers make nectar continuously. Most of the sugar is made in the leaves through the process of photosynthesis. Then, the sugar travels through the connective tissues to other parts of the plant. There are special cells at the base of each flower, near the ovary, that secrete the sugar in to nectar. Providing nectar costs the plant some energy. But of course it also provides pollination, and survival of the species.
Some plants renew their nectar in a matter of 20 minutes, some take a full day. Much of this is dependent on the type of pollinator that visits the flower. For instance, agave plants create a huge reservoir of nectar each evening in their night-blooming flowers, to attract bats. I read this from the American Journal of Botany: "Ideal nectaries should be able (at least in a crude way) to homeostatically regulate their nectar offerings by refilling nectar reservoirs after nectar has been removed, or by readjusting the concentration of sugar as water evaporates." So plants not only adjust the amount of nectar, but the percentage of sweetness, depending on the animal or insect pollinating it. Plants blow my mind.
And bird/insect behavior, where nectar is concerned, does too. Hummingbirds, according the the Native Plant Society, "expand and contract their territories hourly to compensate for shifts in the nectar production of flowers." Reading more about this, it seems hummingbirds also will guard a flower when it knows it is just about to produce a drop of nectar, so that no other bird will get to it first. And according to SpringerLink (a resource for teachers), some native bees use a chemical odor on a particular flower, which repels subsequent foragers.
It makes me wonder if that is why I only see bumblebees on my manzanita, never honeybees?
All of this is pretty interesting and will need more research. I also have an email in to my biologist neighbor, asking for some clarification. I'll let you know what he says.
A couple of other interesting plant items in the garden today. The fava beans are starting to bloom!
And I picked some turnips to see if they might be ready. Um, no.
They're so tiny! I've never grown turnips before, so I didn't know what to expect. Anyway I ate these raw (one bite apiece) and they were very refreshing, a lot like kohlrabi, but spicier. I look forward to having bigger ones soon!