Could be intermittent water shortage or even herbicide (carryover or drift).

What is in your potting mix?

And where are the plants growing? Indoors? Outdoors? Greenhouse?

http://forums.gardenweb.com/discussions/2103613/distorted-naga-leaves?n=31

Ok, I'm still looking into this. I've added a lot of calcium to all the plants. On some of them I've put systemic (screw organic). I'm going to compare and see the difference. Possible causes:

1. Intermittent water shortages. Yes, I'm guilty of this.
2. Spider mites
3. General bug damage
4. Lack of calcium.

All pictures above are of outdoor plants. I have some plants indoors in party cups. They are showing the same symptoms, which leads me to believe this is a calcium issue and not a pest issue. More to come.

Have you checked the plants in the morning when the sun has just come out? (like maybe between 7 and 8:30 AM.) Some critters appear to be more active around that time or so.

Although the leaves do look like they may be exhibiting calcium deficiency symptoms, I don't see any vein deformities without looking closer. I'm not saying vein deformities are required for it to be a deficiency, but it's just an observation that may or may not turn out to be useful.

Erratic watering ... the leaves aren't able to completely grow to mature size because it takes adequate water to make that happen. So you get these deformed ones, and they won't recover. They work as leaves, but they just look wonky.

Consistent but low water makes smallish, but undeformed leaves, tough ones.

Consistent abundant water makes large, lush but tender leaves.

Hi everyone. I tested this out and found the answer--it's a calcium deficiency. I have two Douce D'Espagne plants. One of them, I put a ton of systemic (toxic levels making the plant inedible). The second plant I gave it a ton of calcium. Since we last spoke, the plant with the calcium is growing faster and with normal leaves. The plant with the systemic is much smaller (while still dark green) and it's still growing wrinkled leaves.

Thanks to everyone for your feedback.

I used the following to resolve the issue.