If I'm right—if reading source code requires identifying parts of speech—then familiarity with syntax and grammar is important to programming as an adept.
Consider Damian Conway's SelfGOL. As an experienced Perl programmer, I can pick out various pieces of the code at a glance. There's an assignment. There's quoting. That's a variable. That's a list slice.
If you've never encountered Perl before (or programming in general), you
might recognize some English words, such as
die, and that's all.
One of Perl's design ideas borrowed from linguistics is that "different
things should look different". To novices, everything looks
$name isn't obviously a single chunk. It's an English
identifier and one of several punctuation symbols apparently sprinkled at
random throughout the program.
Good use of whitespace helps. So does the good use of parentheses as grouping constructs (though as in prose, they often get overused by novices).
One of the most subtle mechanisms to identify individual chunks floating in a sea of code is with syntax highlighting. I can't prove this. I haven't studied it in repeatable situations. Even so, I hypothesize that (modulo color choice concerns) merely highlighting different types of terms in the grammar in different ways will help novices understand how to pick out individual chunks in code.
This requires training. This demands practice. Unless you spend time reading code, you won't understand how expressions fit together, and you have little hope of understanding code. I believe it's impossible to skip this step, and thus I don't care if someone who's used C or ML has trouble reading Perl 5 code. Of course people have trouble reading when they don't know the grammar.
(Don't worry, Lisp fans. Homoiconicity—apart from additional complexity of quoting forms and reader macros—means that novices have to spend their time learning to recognize idioms and abstractions at a level higher than tokens and chunks without the benefit of patterns of chunk types as mnemonics to idioms. Then again, I think in patterns, rarely words.)