Has Apple done away with the plant identifier through photos app?

Visual Lookup is available.

Press and hold on the image, and select Look Up from the pop-up. Or tap the button.

• Use Visual Look Up to identify objects in your photos and videos on iPhone - Apple Support

Visual Lookup does need a connection into Apple, as well as some other requirements.

• iOS and iPadOS - Feature Availability - Apple
• Models that support Live Text, Visual Look Up, and lifting a subject from the background - Apple Support

BethDRSRDP wrote:

"Visual Lookup". I should have used the proper terminology; thank you! I don't have Visual Lookup on my phone, but I did. That's why I'm asking this question. Did Apple decide to do away with it on iPhone SEs?

iPhone SE is not in the list of supported devices linked earlier.

There’s a complaint in the comments about the feature not being available on an iPhone SE 2nd (2020) from iOS 17.5 a while ago on the Apple Youtube video (below) for the feature, so this (lack of) support doesn’t seem to be recent:

Related: Look up what's in a photo with your iPhone or iPad - Apple Support