The chemical term you are looking for is "hypergolic" and it means spontaneously causes ignition. There are all sorts of chemicals that are hypergolic with other specific chemicals but very few chemicals are hypergolic with most other chemicals.
I'm going to answer your specific question but follow it with a more general description and interesting articles (interesting if you like the topic that is).
I didn't find much that was directly (meaning without other chemicals present) hypergolic with hydrochloric $ HCl $, however, there are some chemicals that are hypergolic with sulfuric acid ($ H_2SO_4 $).
- Ether (burns vigorously)
- Nitric Acid (vigorous reaction but no flame)
- Potassium Perchlorate (explodes)
- Potassium Perchlorate + sugar/starch
Here's some discussion on a science board about what chemists have found react hypergolically or explosively.
Here's a list of videos which show the same.
The problem with a plant carrying a digestive chemical which reacts so strongly with the chemistry of other living things is this: creatures evolved on the same planet, share the same chemistry. Meaning that plant contains chemicals which can cause itself to spontaneously burst into the flame if its reservoir of that chemical is ruptured.
Imagine an explore hacking his way through a jungle with a machette. He accidentally hits this "flame bush" and ruptures its digestive sack - immediately causing the plant to burst into flame. If any of that fluid sprayed out of the sack, say onto another plant or the explorer, then adjacent plants and even the explorer also burst into flame.
There are chemicals which are hypergolic with many other chemicals. You might find the discussion in Sand won't save you this time discussion amusing or interesting.
The chemical is called chlorine trifluoride ($ ClF_3 $ ).
There’s a report from the early 1950s (in this PDF) of a one-ton spill
of the stuff. It burned its way through a foot of concrete floor and
chewed up another meter of sand and gravel beneath, completing a day
that I'm sure no one involved ever forgot. That process, I should add,
would necessarily have been accompanied by copious amounts of horribly
toxic and corrosive by-products: it’s bad enough when your reagent
ignites wet sand, but the clouds of hot hydrofluoric acid are your
special door prize if you’re foolhardy enough to hang around and watch
”It is, of course, extremely toxic, but that's the least of the
problem. It is hypergolic with every known fuel, and so rapidly
hypergolic that no ignition delay has ever been measured. It is also
hypergolic with such things as cloth, wood, and test engineers, not to
mention asbestos, sand, and water-with which it reacts explosively. It
can be kept in some of the ordinary structural metals-steel, copper,
aluminium, etc.-because of the formation of a thin film of insoluble
metal fluoride which protects the bulk of the metal, just as the
invisible coat of oxide on aluminium keeps it from burning up in the
atmosphere. If, however, this coat is melted or scrubbed off, and has
no chance to reform, the operator is confronted with the problem of
coping with a metal-fluorine fire. For dealing with this situation, I
have always recommended a good pair of running shoes.”
Put chemicals like these under the title "if you discover someone messing with these, run away from them as fast as you can".