Do Passives Crossover?

I've been listening to a lot of pod casts and frequenting many sites but this odd question hasn't fully been answered to my satisfaction. So, I'll reach out the smartest gamers I know... :)

Each profession has 3 specialty lines (like for Dragonknight: Ardent Flame, Draconic Might, and Earthen Heart) and 4 passives with each specialty. My question is: Using Dragonknight as an example, if I max out all 4 of the Ardent Flame specialty passives and then load up on passives from say, Earthen Heart, do those passives always apply regardless of what specialty I use (I know some are based on the number of skills in the specialty)? Bear with me a moment... then weapon passives, guild passives, armor passives, etc. Once you have that passive, is it always 'on' and applicable regardless what skills you use (if it's requirements are met)?

I hope my question made sense. Again, I understand some are based specifically on if you're wielding a destruction staff or light armor... but some from the 3 specialty lines of each profession could theoretically 'crossover' (i.e., Iron Skin from Draconic Might, Battle Roar from Earthen Heart, or Warmth from Ardent Flame (if wielding a fire-based Destruction Staff).

Let me know what you all think. Thanks!

Yes they do "crossover" as long as their conditions are met, if they have conditions. Some of the tooltips for passives say "increased damage with _____ skill line" so obviously those do not apply to other skill lines. Also as you mentioned, some are dependent upon how many skills from a particular skill line you have on your skill bar. I don't think you can load up on a particular skill line on your weapon swap bar and switch back to your main weapon and have those passives apply. They only apply to the skill bar you have active at the time. So pretty much if you read the tooltips carefully, you can figure out if a particular passive will crossover to other trees. I don't think it would be possible for ZOS to turn passives on or off based on invisible conditions or which skills you use. 

That's what I was assuming - your comment is helpful, thank you!