( ( ( ( ( Frost ( -LRB- ( ( also ( called ( ( white or ) hoarfrost ) ) ) -RRB- ) ) ) ( occurs ( when ( ( air temperatures ) ( dip ( below 32F ) ) ) ) ) ) and ) ( ( ice crystals ) ( ( ( form ( on ( the ( plant leaves ) ) ) ) , ) ( ( injuring and ) ( sometimes ( killing ( tender plants ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NP (NNP Frost)) (PRN (-LRB- -LRB-) (VP (ADVP (RB also)) (VBN called) (S (ADJP (JJ white) (CC or) (JJ hoarfrost)))) (-RRB- -RRB-))) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (NN air) (NNS temperatures)) (VP (VB dip) (PP (IN below) (NP (CD 32F)))))))) (CC and) (S (NP (NN ice) (NNS crystals)) (VP (VBP form) (PP (IN on) (NP (DT the) (NN plant) (NNS leaves))) (, ,) (S (VP (VP (VBG injuring)) (CC and) (VP (ADVP (RB sometimes)) (VBG killing) (NP (NN tender) (NNS plants))))))) (. .)))
Frost (also called white or hoarfrost) occurs when air temperatures dip below 32F and ice crystals form on the plant leaves, injuring and sometimes killing tender plants.
(ROOT (S (NP (NP (DT The) (NN ice) (NNS crystals)) (SBAR (WHNP (WDT that)) (S (VP (VBP form) (PP (IN on) (NP (DT the) (NN ground))))))) (VP (VBP are) (VP (VBN called) (S (ADJP (JJ frost))))) (. .)))