Summer and apple: history of a Nostratic Wanderwort

In Greek mythology, Hēméra was the primeval goddness of the day. From this word and Armenian awr 'day', Indo-Europeanists such as Mallory-Adams¹ reconstruct an IE protoform *h₂ēm-ər- '(heat of the) day', which I link to Semitic *ħamm- 'to be hot; warm'², with the voiceless pharyngeal fricative ħ corresponding to "laryngeal" h₂. 

It doesn't take a long stretch of the imagination to devise a derived variant *HVmV-lV/HVmVlV which gave (with metathesis) Nakh-Daghestanian *mhalV/mhanV- 'warm' and IE *mah₂lo- 'apple', with a straightforward semantic drift from 'warm (season)' to 'fruit'. Several IE languages of North Europe (Celtic, Germanic, Balto-Slavic) reflect a protoform *abVl- 'apple' (< *amHVl-?) which is regarded as a Paleo-European substrate loanword by some specialists.⁴

A variant *ʕu-malV/*ʕu-manV would be the origin of Uralic *omena/omVrV 'apple' as well as  Basque udare, udari, madari 'pear'³ (with denasalization and further delabialization), umao (B), umo 'ripe, seasoned'.  This makes sense because the apple tree is originary of Kurdistan, precisely in the area where Nostratic was presumably spoken.

On the other hand, we've got yet another IE variant *sam-/*səm-ro- 'summer'⁴ and Hittite sam(a)lu- 'apple (tree)'.⁶⁵

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¹ J.P. Mallory & Q.D. Adams (2006): The Oxford Introduction to PIE and the PIE World.  

² Also cognate are Hurrian am- 'to burn' and (possibly through an Etruscan intermediate) Latin amāre 'to love', amor 'love'.

³ For example, Theo Vennemann links it to Afrasian *ʔa-bul- 'male genitals', which (in his own words) is "semantically unsatisfactory although phonetically perfect". See T. Vennemann (1998): Andromeda and the Apples of the Hesperides, in Europa Vasconica, Europa Semitica, 591-652.

⁴ The ablaut form *sem- usually quoted in dictionaries isn't attested anywhere.

⁵ Explained by ortodox IE-ists such as Kloekhorst as the result of a "s-mobile".