See if a type variable represents a superclass of a given Class

Given a class

class EnvironmentHolder<V> {
    protected Map<String,V> environment;

    // Get the Type of V using Google's Guava library; this part
    // works okay
    protected final Type VALUE_TYPE = new TypeToken<V>() {}.getType();

    ...

    public void importEnvironment(Class aClass) {

    }
}

where V is some reference type, I'm trying to collect all of the static members of aClass which are "assignable to" a class of type V — that is, those which are subclasses, implementations of, or the same class as V.

How do I do this? I'd like to use the following:

for (Field field : aClass.getFields()) {
    ((Class) V).isAssignableFrom(field.getType())
}

I see that Class is indeed an implementer of Type, but I'm not sure how to perform a cast safely. (Type also encompasses non-reference types, which are not Classes.)

NB: Please don't say, "Type erasure preludes doing this at runtime" until you have thought it through. A fair number of questions have that as a virtually automatic response, which would seem to imply that a reflection API is impossible to implement in Java.

Thanks!