Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 6 · Calendar, Muhurta Elements
कालमानं मुहूर्ताङ्गानि च
तारासंख्याश्च विज्ञेया दस्रादीनां पृथक् पृथक् ।या दृश्यंते दीप्तताराः स्वगणे योगतारकाः ॥ २०३ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 203.
The number of stars of Ashvini and the rest should be known, one by one. The bright stars seen in each group are the yogataras (the chief star of a nakshatra).
Simple meaning: Each nakshatra has a known number of stars. The bright ones are its chief stars.
वृषो वृक्षोश्वभायाम्यधिष्ण्येयमकरस्तरुः ।
Each star has its own tree. Krittika has the fig and Rohini the jambu.
इन्दुभात्खदिरो जातः कृष्णप्लक्षश्च रौद्रभात् ।
Mrigashira has the khadira, Ardra the black fig, Punarvasu bamboo and Pushya the peepal.
सर्पधिष्ण्यान्नागवृक्षो वटः पितृभसंभवः ।
Ashlesha has the naga tree, Magha the banyan, Purva Phalguni the palasha and Uttara Phalguni the aksha.