A half-orc has a direct parent who is an orc. A sorceror with the Orc bloodline has orcish blood somewhere in their history, regardless of their race. A human with orc blood does not a half-orc make. A sorceror with the Arboreal bloodline can't photosynthesize, so you don't get to have tusks.
But, there is an alternative. Use the Racial Heritage feat from the APG and you can take all the half-orc feats and traits you want as a human.
Where is the Orc bloodline from anyway? I've seen it mentioned a few times on the forums, but I'm not sure of the sourcebook.
Just guessing but it might be in the Orcs of Glorian under the Players Companion line. I took a read of the description, no mention there but it does mention Orc tribal magic.
It's in orcs of Golarion p.14
Also this bloodline's arcana gives you the orc subtype.
I would rule that having the Orc subtype counts as being an Orc for feat prerequisites. This interpretation does mean that "orc or half-orc" is redundant, but I stand by it.
Also this bloodline's arcana gives you the orc subtype.
Well, that's good to know. Essentially means that, like a half-orc, you count as your race (human in the OP's case) and an orc for the purposes of spells, effects, magic items, and so on, similar to this:
Orc Blood: Half-orcs count as both humans and orcs for any effect related to race.
My point still stands though. The subtype benefits apply only to effects, not feats or traits. A half-orc couldn't take the Racial Heritage feat, for example, and be considered human, orcish, and dwarven. The Orc subtype does not make you a half-orc, and the prerequisites for the half-orc feats are pretty clear; you have to be a half-orc to take them (even a full orc can't take those feats!). In other words, if your race is listed as anything other than half-orc, no matter your subtype, you can't take them. The only way around it is through the feat I indicated earlier or asking your GM to houserule it.
Shiverscar, I can't disagree. Now I'm left mystified as to why standard orcs can't burn a feat to get tusks, but half-orcs can...
Mysteries of the blood, I suppose...
Or oversight since orc isn't a player race.
Or oversight since orc isn't a player race.
Nope, they didn't overlook full orcs. There are about 3 or 4 feats in the APG that list "half-orc or orc" in the prerequisites; some even include dwarf, I guess to round out the 'hardy' races. Just certain feats (and traits) are unique to half-orcs.
Maybe the weaponized tusks are a unique aberration, brought on by the intermingling of human and orc genes?
...I'm stretching, but there's likely a reason that some feats are unique to half-orcs, while others allow orcs to take them. I'd lean towards balance, and the idea of making the core races more appealing than the monstrous races, but that's just my interpretation.
...I'm stretching, but there's likely a reason that some feats are unique to half-orcs, while others allow orcs to take them. I'd lean towards balance, and the idea of making the core races more appealing than the monstrous races, but that's just my interpretation.
Really, I would say the problem lies in treating half-human hybrids as full races in their own right.
A sorceror with the Arboreal bloodline can't photosynthesize, so you don't get to have tusks.
I know this is totally irrelevant to the discussion, but the Verdant bloodline (I don't think there's actually one called Arboreal) does grant photosynthesis at 3rd level.