What does this preflower look like?

I'm not sure but it looks like a white hair starting to poke out of it. It's day 33 since they sprouted so it's probably about time to be seeing some preflowers on these NLxC99s. :thumbsup:

still to early to tell, theres not defenative evidence there in the circle

look for double hairs coming out of the calyx

It's not for certain but I'm going to go with female. Post some pics in about 4-5 more days. We should be able to tell for sure by then.

I'm seeing white hairs on two of the three plants. The first pic is actually the only one I can't see white hairs on. Looks like it might be male. The last 3 pics are of the other two plants.

You can't see it in the pics but on all 3 plants the tips and serated edges of the leaves are yellow. Just the very tip where it comes to a point like a little dot the size of a grain of sand right on each point on the leaf. I think this is nute burn but I'm not sure. I'm feeding them Botanicare Pure Blend Pro Grow, Liquid Karma, and Superthrive every three days when I water.

Those all look too early to tell right now. Most of what you have circled look like *stipules* around the petiole. These are little outgrowths at the base of a leafy stem. They look like preflowers but are really just part of the vegetative phase. The preflowers will appear *very near* these stipules, though, and probably cluster around them (especially for male plants). In females, they won't be as dense as the males at first, but a VERY distinct occurance of white hairs will appear. Here are a few pictures of a female preflower and male to help differentiate between a stipule, female, and male... Hope this helps, and nice grow!

--Unfortunately, I would say the first pic looks like it may have male preflowers. There are small buds starting to form which is typical of a male in early flower. Hopefully this is only limited to the one plant if it turns out to be male....

As for your suspected burn; I would say no worries if it is very limited. It is not uncommon at all for me to see this type of burn on the leaf tips, and it usually has no effect on the grow as long as it is closely monitored and corrected (I say its best to flush when I see tip burn like that; but don't overcontrol)