The poet does not say “eyes like narcissi.” He uses the name narjis directly for the eyes. This is metaphor rather than a plainly stated comparison.
«لُؤْلُؤًا مِنْ نَرْجِسٍ»
Pearls from a narcissus—that is, tears coming from an eye.
Reading every noun literally would produce an impossible botanical scene. Recognising the implied human situation restores coherence and allows the imagery to be appreciated as deliberate poetic craft.